Created attachment 34293 [details]
When switching from full-screen 3D game (Urban Terror) back to X (using alt+tab), the desktop appears and the machine hangs instantly and completely (does not respond to pings).
Created attachment 34294 [details]
Looks like MESA bug. 7.7 hangs, 7.5 does not.
7.6 hangs too.
Does booting with kernel parameter radeon.modeset=1 help?
KMS was completely broken on this system last time I tried it (3D did not work at all).
> --- Comment #5 from Ondrej Zary <email@example.com> 2010-04-06 02:30:29 PDT ---
> KMS was completely broken on this system last time I tried it (3D did not work
> at all).
might let you capture some useful kernel messages just before freeze.
If normal boot doesn't produce any useful information from the freeze
booting with drm.debug=15 would give lots of debug information.
That sounds like serious bug that should be fixed. Is there open bug
report about your KMS problems?
Created a bug report about KMS problems here: https://bugs.freedesktop.org/show_bug.cgi?id=27517