bts forwarded 487672 http://bugzilla.kernel.org/show_bug.cgi?id=10965 thanks I forgot to mention : If I switch to either screen completely (crt=on + lvds=off OR crt=off + lvds=on), the problem doesn't occurs ! I have tried xserver-xorg-video-intel 2:2.3.2-1 , but it didn't help. I have tried to remove libgl1-mesa-dri , but it didn't help. Franklin