Problem with frozen windows corners in beryl

[zenco]

Hi does anyone know how to fix this

http://img32.picoodle.com/img/img32/...3m_2d3d2c7.jpg

i usually get rid of it by refreshing windows manager but its frustrating doing it each 2 min, the problem start when i click right click on anything like a window or in the desktop. I'll be gratefull if someone tell me anything related to this , thanks