QUOTE(brandogg @ Oct 14 2008, 03:56 PM)
If it's only crashing with DVD based games (demos run fine, XBLA games run fine, etc), then it's probably your HDD's cache. You can clear it...I forget the code but it's all over these forums.
Go to your dashboard, then go all the way to the right tab and click memory.
Press Y on the HD symbol and then press X,X,Left Bumper, Right Bumper, X,X. Once you do this a messsage will appear saying: Do you want to perform maintenance on your Xbox 360 storage devices? Hit yes.
See if that helps... you can also try holding the sync button down while turning it on.