anyone else having boot issues?

[stratacast]

Out of the blue it seems like my computer has problems where it hangs on boot, but only with the current kernel (4.4.0-28-generic), but going back to 4.4.0-24-generic seems to have no problems. I've seen others having this with other Ubuntu 16.04 versions and it seems Nvidia is the culprit and they say their fix is setting nomodeset as a boot option but that didn't work for me. What's also interesting is if I boot into 4.4.0-24-generic then going back to 4.4.0-28-generic is just fine. Kubuntu was installed in UEFI mode

[GreyGeek]

...What's also interesting is if I boot into 4.4.0-24-generic then going back to 4.4.0-28-generic is just fine. Kubuntu was installed in UEFI mode

"going back" = warm boot?

[stratacast]

It can be a reboot or a cold boot. I will try the 4.4.0-28 kernel and after 3 hard shutdowns I switch to 4.4.0-24 and the problem goes away

[GreyGeek]

Did you use systemd-analyze or journalctl in an attempt to identify the problem?

[stratacast]

When would I run those commands?

[GreyGeek]

After (IF?) you bring your desktop up open a konsole and issue them. If you can't get to a desktop then use the recovery option on the grub menu, and select the root option. As root you can run the commands there on the command line interface (CLI).

The systemd-analyze command shows kernel space and user space times. The systemd-analyze blame command gives the times for all processes that run during the kernel and user space boot process. The journalctl command gives the same as systemd-analyze blame but includes the desktop processes as well. If you create the file
/etc/systemd/journald.conf
and it it put:

#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.
#
# Entries in this file show the compile time defaults.
# You can change settings by editing this file.
# Defaults can be restored by simply deleting this file.
#
# See journald.conf(5) for details.

[Journal]
#Storage=auto
Storeage=persistent
#Compress=yes
#Seal=yes
#SplitMode=uid
#SyncIntervalSec=5m
#RateLimitInterval=30s
#RateLimitBurst=1000
#SystemMaxUse=
#SystemKeepFree=
#SystemMaxFileSize=
#SystemMaxFiles=100
#RuntimeMaxUse=
#RuntimeKeepFree=
#RuntimeMaxFileSize=
#RuntimeMaxFiles=100
#MaxRetentionSec=
#MaxFileSec=1month
#ForwardToSyslog=yes
#ForwardToKMsg=no
#ForwardToConsole=no
#ForwardToWall=yes
#TTYPath=/dev/console
#MaxLevelStore=debug
#MaxLevelSyslog=debug
#MaxLevelKMsg=notice
#MaxLevelConsole=info
#MaxLevelWall=emerg

You will create a persistence mode which will store each boot log. You can recall a specific boot log using
journalctl -b -n
where n is 0 for the current boot, 1 for the previous boot, 2 for the boot before 1, etc...
From the man journalctl are some examples:

EXAMPLES
       Without arguments, all collected logs are shown unfiltered:

           journalctl

       With one match specified, all entries with a field matching the expression are shown:

           journalctl _SYSTEMD_UNIT=avahi-daemon.service

       If two different fields are matched, only entries matching both expressions at the same time are shown:

           journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097

       If two matches refer to the same field, all entries matching either expression are shown:

           journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service

       If the separator "+" is used, two expressions may be combined in a logical OR. The following will show all messages from the Avahi service
       process with the PID 28097 plus all messages from the D-Bus service (from any of its processes):

           journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service

       Show all logs generated by the D-Bus executable:

           journalctl /usr/bin/dbus-daemon

       Show all kernel logs from previous boot:

           journalctl -k -b -1

       Show a live log display from a system service apache.service:

           journalctl -f -u apache