http://forums.nvidia.com/index.php?showtopic=56078

Hi ive just found a serious problem, the problem started when I minimised COD4 to paste an ip address to a friend on irc. The problem is that everytime i try to quit any game, or even uninstall graphics drivers, or even change my screen refresh rate, and even sometimes on boot up my monitor loses the signal and just goes to a blackscreen, in the background you can hear the software etc still working.

Can anyone provide me with a fix, ive seen on this forum somewhere a guy with a floating box/blackscreen problem, i dont have the floating box but I do have the black screen problem and it sounds exactly like hes gotten into the same situation.

PROBLEM SOLVED

its a bug somewhere down the line, were if your refresh rate is different then your windows refresh rate it will cause the black screen, now this is strange as my refresh rate was different in both areas for ages without no prob, but obviously since a driver update thats changed things. So yeah match ur refresh rates in game with your windows if you encounter any black screens.