The Dark side of the force cloudes everything!!!
Seriously, i couldnt get my KOTOR games to load, even though there wernet any scratches on the discs.
My advice is pull the cables out of ure XBOX, and blow into the fan, then a cloud of dust should cover the look on ure face, then buy a dvd lens cleaner and an xbox dvd playback kit, and clean the lens, my three year old xbox runs like a new born.
If that dont work send another post