I recently started having crashing problems as well.
Running Vista64 with a 8800GTS 640mb.
I am an ARMA admin over at Tactical Gamer, and found this thread while looking for a cure. I have also been talking to other TG players and it looks like a ton of them are having crashing problems with Nvidia cards. Mostly 8800's, but one guy is running a 9600GT.
I updated to the newest official drivers last night to check them, and have had 2 crashes since. At first I thought it might be heat related, but I have an Antec p182 case (best case there is, if anyone is looking at cases) and it has awesome airflow. Everything is running cool. This just started about a month and a half ago, and seems to have become more frequent. Some nights no crash, others 3 crashes.
I am also getting an windows error report that points to Nvidia driver failer when it reboots.
By the way, my crash is like this. Playing anything, nothing really going on in particlular, and the screens (dual monitor setup) kind of flicker for a moment, then main one goes black, and the other has some random bands of stuff on the screen. Sometimes sounds keep repeating themselves over and over, or I can still hear comms like nothing is wrong.
It then goes black on both screens, and will stay that way till blue screen of death after a few mins, or I just have to hard crash the system.
There are supposed to be new drivers released in the next couple of weeks that include the physiX stuff, and I guess I will wait and try them out. If that doesn't work I am really thinking about going ATI. It really sucks as admin to keep crashing, and even worse when you are flying a blackhawk full of troops and you crash out. Guys in the back are not very happy.
Article about the new drivers:
http://techreport.com/articles.x/15261