My MBP had its logic board replaced yesterday and I thought it'd work fine. I booted into Windows via Bootcamp and started playing Battlefield 2142 after about one minute or so the whole thing locked up so I had to hard-reset. I tried multiple times and it showed the same sympton. Then I booted into OS X and played Unreal Tournament 2004, same problem, entire system locked up and forced me to hard-reset. And I am able to duplicate the same thing over and over again. However, normal browsing or just generally "using" the computer never crashed it. I guess it's safe to say that the system only crashes under heavy stress? Is it a defected logic board that they put in? Or what else could it be? This has never happened before. Thanks for all your comments.