I don't know for sure, but if you hit f8 during the boot, and go to advanced menu, there is a selection for basic video or something like that. You might try that to see if it will allow you to boot normally.
If it works, check you video and perhaps change resolution or check to see what driver it is using. Maybe the game messed up some settings.
If that doesn't work, maybe a startup repair from the same advanced menu on boot.