I noticed a serious problem while trying to play OOlite ( http://www.oolite.org/ ) game:

When using "virtual desktop" (with panning), while trying to move/resize game window - or just to "pan" visible screen area - it locks whole system completely. Even "power off" button doesn't work, which is suggesting, that the system may be completely hung up (the title theme music drums are repeated in a short loop like kinda machine gun). I hadn't such behaviour formerly, when using NVidia with their "closed" drivers.

Slackware 14.1 32bit, X.Org X Server 1.14.3, kernel 3.17, OOLite 1.80

Output of my xrandr:

Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 4096 x 4096
VGA-0 disconnected (normal left inverted right x axis y axis)
DVI-0 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 473mm x 296mm panning 1680x1050+0+0
 1680x1050 60.0 +
 1280x1024 60.0 
 1440x900 59.9 
 1280x800 59.9* 
 1024x768 60.0 
 800x600 60.3 56.2 
 640x480 60.0 
 720x400 70.1 
S-video disconnected (normal left inverted right x axis y axis)

Easy to reproduce:

1. Start XWindow in "virtual screen" mode (the bug doesn't occur while not using virtual screen).
2. Open game window.
3. Try to pan visible screen area, or to move game window. Very soon lock-up occurs.