blender 2.5x crashes after awhile

Hello everyone, my problem is: since version 2.5x blender does not work:mad:! I start the programm, everything is fine, but after ten minutes or sometimes after 1 minute the whole UI turns dark grey and the window where the mouse is flickers that makes me insane :D!
I did not find a thread that covers this problem but i am sorry if there is one
Peace to the blender community

for me installing the latest graphics drivers fixed this

Thank you very much for your reply but on my computer it still turns grey ! Maybe the damn thing is just too old. Nevertheless thanks!