Are you playing the game off the DVD, or installed to the hard drive?
One person had issues with the game crashing when entering rooms, or shortly after, which installing to the hard drive resolved. After trying the game once off the DVD, I installed it just to help with noise and performance.
I had 3 lockups playing on Xbox (all within a couple minutes of saving, though), one of which was as the screen darkened just before a loading screen. Each time was after the Xbox had been on all day, so I suspect heat may have been an issue.
