I was flipping through some videos, I would play one, watch it a bit, then quit Totem and double click another to play it. I did this three or four times but then the next time, on quitting Totem with the video playing, hit an X hang/crash (the screen was frozen, mouse pointer would move, couldn't switch to a VT, could ssh in and see the crash at the end of the X log). X log attached. This is my laptop, the Vaio Z.