Okay, honestly, I'm stumped. The ONLY other thing I can come up with to try, would be set your game resolution low, put all your options down to the minumum (no acceleration on your sound, reduce the AI, view distance, etc), shut off the sound, etc. In short, do everything you can to minimize the processing load on your machine. See if THAT helps, if it does, I would say that it indicates that something, somewhere - hardware-wise - is being stressed to the point of crashing your game.