Hello, I am having a little bit of an issue which may be a driver bug.
Noticed on OpenSuSE 11.2 / KDE 4.3+
Occasionally on login, when Compiz starts up and takes over compositing from KWin, my GTX 470 display goes black and cannot be interacted with. I am forced to restart X until I get lucky and the problem doesn't happen. This can happen any time Compiz takes over compositing, not just at X Start (if I restart Compiz to apply certain changes, for example).
nvidia bug report here
I have 5 screens, two TwinView configurations, however I believe this problem can be reproduced with two separate X screens on separate cards. Notably, KWin was running -only- on the affected card (KWin4 does not support multiple X Screens).
Let me know if you need any additional information.