I think I have got the same bug on my laptop that uses the free intel graphics driver - but not on my desktop PC that uses fglrx. Both systems use up to date Squeeze amd64 and iceweasel.
I agree with Henrik that X doesn't actually crash. The fullscreen image of the video freezes, but when trying to leave fullscreen the video goes on playing (I hear the sound) and the mouse cursor also acts like I'm back in non-fullscreen mode, i.e. it changes at the border of windows for resizing etc. However I haven't found a way to get rid of that frozen fullscreen video image, so I also had to kill X to get a usable desktop again. Furthermore /maybe/ this happens when something is displayed on top of the fullscreen image, like a message from xosd-bin (when I press the laptops volume buttons I have messages displayed) - but this could have been a coincidence. Cheers, - Daniel -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org