Boot Device Sequence

[Don]

I'm running Precise. For reasons I do not understand, my installation now insists that it will boot only from a CD. It used to boot from the first hard drive, which is what I want. I did not *deliberately* make any changes. Oddly, if I put a Precise installation disk in the CD drive and then activate "Boot to first hard drive" from its menu, the machine boots perfectly. I do not know what file to look in to see what Precise (on the hard drive) thinks the boot device sequence ought to be. I did some on-line research and ended up looking for "menu.lst," but there is none. I'll be grateful for any clues as to what I should do next.

[GerardV]

The same thing happened to me once on a old Acer laptop. It would only boot from a cd or a network, although i had a fresh install of 11.0 . and winxp on it. Turned out, if i remember correctly, than partition table of the HDD was corrupted and the system did not recognize it to boot from. After i re-formatted it, and re-created a new partition table, everything was fine.

[vinnywright]

what exactly are you seeing when you start the computer without a cd in the drive ?
did you do any partition changing or reformatting ?

and post the contents of /boot/grub/grub.cfg after you get logged in as you are currently doing .

VINNY

[blackpaw]

Could the drive have got removed off the boot list in the bios?

[Qqmike]

What blackpaw said, my first guess, too:
Re-boot, enter your BIOS setup menu, exam your boot device list, make sure CD is as listed first boot device, then make sure at least one HDD is listed after the CD.

[Don]

My thanks to all for the quick replies. I'm reluctant to try Gerard's idea, at least at first, because of the amount of rebuilding it requires. The machine is at home; I'm at work now. When I get home this evening, I'll post the contents of grub.cfg, as Vinny requested, and I'll check the BIOS setup menu.
I'm very grateful for the help.

[luckyone]

You could also try an update-grub after getting the HDD booted.

[Don]

This is in further respone to Vinny. When I start without a cd in the drive, I see the normal startup lines until it gets down to "Boot from CD" and stops. It never gets past that. I have not done anything with partitions or formatting since I first installed Precise months ago.
Here are the data from grub.cfg:
************************************************** ************************************************** ***************
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}

function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}

function load_video {
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
}

insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=auto
load_video
insmod gfxterm
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
set locale_dir=($root)/boot/grub/locale
set lang=en_US
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ]; then
set timeout=-1
else
set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
if background_color 75,75,75; then
clear
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
set gfxpayload="${1}"
if [ "${1}" = "keep" ]; then
set vt_handoff=vt.handoff=7
else
set vt_handoff=
fi
}
if [ "${recordfail}" != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode
if [ "${linux_gfx_mode}" != "text" ]; then load_video; fi
menuentry 'Ubuntu, with Linux 3.2.0-33-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-33-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-33-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-33-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-33-generic ...'
linux /boot/vmlinuz-3.2.0-33-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-33-generic
}
submenu "Previous Linux versions" {
menuentry 'Ubuntu, with Linux 3.2.0-32-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-32-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-32-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-32-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-32-generic ...'
linux /boot/vmlinuz-3.2.0-32-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-32-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-31-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-31-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-31-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-31-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-31-generic ...'
linux /boot/vmlinuz-3.2.0-31-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-31-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-30-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-30-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-30-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-30-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-30-generic ...'
linux /boot/vmlinuz-3.2.0-30-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-30-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-29-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-29-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-29-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-29-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-29-generic ...'
linux /boot/vmlinuz-3.2.0-29-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-29-generic
}
menuentry 'Ubuntu, with Linux 2.6.32-42-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-2.6.32-42-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-2.6.32-42-generic
}
menuentry 'Ubuntu, with Linux 2.6.32-42-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 2.6.32-42-generic ...'
linux /boot/vmlinuz-2.6.32-42-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-2.6.32-42-generic
}
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux16 /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
if [ "x${timeout}" != "x-1" ]; then
if keystatus; then
if keystatus --shift; then
set timeout=-1
else
set timeout=0
fi
else
if sleep --interruptible 3 ; then
set timeout=0
fi
fi
fi
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}

function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}

function load_video {
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
}

insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=auto
load_video
insmod gfxterm
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
set locale_dir=($root)/boot/grub/locale
set lang=en_US
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ]; then
set timeout=-1
else
set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
if background_color 75,75,75; then
clear
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
set gfxpayload="${1}"
if [ "${1}" = "keep" ]; then
set vt_handoff=vt.handoff=7
else
set vt_handoff=
fi
}
if [ "${recordfail}" != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode
if [ "${linux_gfx_mode}" != "text" ]; then load_video; fi
menuentry 'Ubuntu, with Linux 3.2.0-33-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-33-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-33-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-33-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-33-generic ...'
linux /boot/vmlinuz-3.2.0-33-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-33-generic
}
submenu "Previous Linux versions" {
menuentry 'Ubuntu, with Linux 3.2.0-32-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-32-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-32-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-32-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-32-generic ...'
linux /boot/vmlinuz-3.2.0-32-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-32-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-31-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-31-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-31-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-31-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-31-generic ...'
linux /boot/vmlinuz-3.2.0-31-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-31-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-30-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-30-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-30-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-30-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-30-generic ...'
linux /boot/vmlinuz-3.2.0-30-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-30-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-29-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-3.2.0-29-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-3.2.0-29-generic
}
menuentry 'Ubuntu, with Linux 3.2.0-29-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 3.2.0-29-generic ...'
linux /boot/vmlinuz-3.2.0-29-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.2.0-29-generic
}
menuentry 'Ubuntu, with Linux 2.6.32-42-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux /boot/vmlinuz-2.6.32-42-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro quiet splash $vt_handoff
initrd /boot/initrd.img-2.6.32-42-generic
}
menuentry 'Ubuntu, with Linux 2.6.32-42-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
echo 'Loading Linux 2.6.32-42-generic ...'
linux /boot/vmlinuz-2.6.32-42-generic root=UUID=726fe199-596b-4f85-beea-0c0ed8b6227a ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-2.6.32-42-generic
}
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux16 /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root 726fe199-596b-4f85-beea-0c0ed8b6227a
linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
if [ "x${timeout}" != "x-1" ]; then
if keystatus; then
if keystatus --shift; then
set timeout=-1
else
set timeout=0
fi
else
if sleep --interruptible 3 ; then
set timeout=0
fi
fi
fi
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
************************************************** ***************************************
I lack the expertise to make sense of it.

[Don]

Problem solved. When I went into one of the sub-menus in the BIOS, the Boot-Harddrive-Priority had gotten messed up. It was listing a USB device, often not present, instead of the hard drive with the bootable partition. I have no idea how it got changed, since it's nothing I would have done intentionally. In any case, I seem to have messed it up inadvertently. Thanks to all for the help, especially Blackpaw and Qqmike, who seem to have nailed it.

[Qqmike]

Don, re your BIOS , "I have no idea how it got changed, since it's nothing I would have done intentionally. In any case, I seem to have messed it up inadvertently."

I've had it happen -- BIOS changing my settings like that on the boot device sequence. Also unexplained. On the Intel boards D915GAV and DG33FBC. (And, yes, I always F10 -- Save and Exit -- correctly!) Glad you got it fixed.