Comment 62 for bug 973096

Fail here too:
Ubuntu 12.04 x86_64
Gnome-shell (happened on Unity, not on 2d/Ubuntu classic/no-effects)
NVIDIA Kernel Module 295.53
01:00.0 VGA compatible controller: nVidia Corporation G80 [Quadro FX 4600] (rev a2)

Previously (drv 295.30) there were "GPU fallen off the bus" error with hard system freeze, now (295.53) I get unexpected, quite random, back to login screen with this in syslog:

May 24 10:20:17 odd-pc kernel: [15728.617119] do_general_protection: 27 callbacks suppressed
May 24 10:20:17 odd-pc kernel: [15728.617122] Xorg[1248] general protection ip:7f60c165a0f9 sp:7fff1bb182b0 error:0 in nvidia_drv.so[7f60c15f8000+6e1000]
May 24 10:20:18 odd-pc gnome-session[1701]: Gdk-WARNING: gnome-session: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.#012
May 24 10:20:18 odd-pc acpid: client 1248[0:0] has disconnected

I had Blender3d+Stellarium (OpenGL apps) launched for some time + some youtube vids in 1080p + playing around with windows in gnome-shell, + left PC for some time till screen-lock to see if it will wake screen/gpu back up (freezes sometime occured there before) to somehow stress the GPU / test various cases - no effect.
And then I got thrown back to login screen doing nothing, so it's quite unpredictable.