What's your video card?
If you're using pre-beta drivers...you might want to look for updates. In my case, fallout3 was looping because of an error in reading the name "ATI Mobility Radeon HD 3650 (prerelease - WDDM 1.1)...the dash is what your suppose to have...but my older drivers used -- (forgot what it's called when you combine 2 dashes). After updating, it became a dash and it worked...try it.
-dcommand3r