Comment 18 for bug 994203

I've been having similar experiences on 64 bit systems, both with an ATI RADEON 4650 in my Desktop, and Intel HD (on chip i5 3210m) graphics. As it affects Noveau, NVidia, ATI and Intel, it really does not seem to be related to graphics drivers.

I suspect this is a much more frequent problem than reported as it requires a fair bit of knowledge to extract the relevant logs upon a crash. Thus the majority of bug reports about this problem get shot down due to "lack of attachments" which obviously require the user knowing how to drop to a shell and copy logs across using the command line. This is a full unrecoverable system hang, just as bad as a Windows BSOD. It is a major bug and needs attention.

The symptoms are as described above: suddenly, for no reason, in Ubuntu 12.04 and 12.10 the desktop will freeze with the launcher on the left and any windows being unresponsive. Widgets in the taskbar at the top continue to remain animated, but none of these respond to mouse clicks. I am able to move the mouse, but nothing responds. I can drop to the shell with Ctrl+Alt+F1. Restarting Compiz does not fix the problem. Restarting Unity does not fix the problem. The only thing I can do is reboot the system which obviously causes DATA LOSS from any open programs.

While in the shell I took the liberty of making copies of syslog, dmesg, Xorg.log and kern.log. Hopefully this will shed some more light on the issue and stop Ubuntu devs from passing the buck to the graphics drivers about this important bug.