Comment 32 for bug 1033533

Ok, it seems that your system hangs first, and nouveau dies here later. At this point you were already crashing, so this crash bug is mostly a result of another bug triggering first. The gpu is already non-responsive at that point, which makes the xorg crash not really a surprise.

Unfortunately in some cases I don't see exactly what's causing it, but in all cases it seems that they have in common that the gpu locks up first, for various reasons..