I've been playing Bioshock for some time now (2nd time through the game) and suddenly the video is choppy.
I took the game back to the store and got a new one(even though it looked fine - no scratches or anything)...still choppy.
I created a new profile and started a new game...still choppy.
Dropped the output to 720 from 1080...you guessed it, still choppy.
All my other games (Gears of War, R6 - Vegas, Guitar Hero II & III, COD4) all work fine.
The XBox 360 is about 4 months old.