New problem playing games on MacBook Pro

[Lucky13oz]

Hi all, I am having a problem playing games on my MBP its the 15 inch 2.66GHz 4GB Ram and the Nvidia 9600M GT. I have never had any problems playing any of the games before. A couple days ago I was Playing Mass Effect 2 and it locked up. I tried to resolve the issue so far by checking for viruses and updating my bootcamp drivers. It locks up playing several of the other games now too like Dawn of war II and Fallout 3. I have never had any issues before so I am at a loss of what to do next besides reinstalling windows 7. I was kinda hoping someone could give me some advice so I wouldn't have to do that. Thanks!!