CRAP! Im haivng the same problem, game wont load level 4-2 no matter what I do - and my game never crashed until I tried to load that level.
Tried local co-op but same thing, and I cant get an online game. This is very, very annoying!
I also went through the standard list of fixes like install, clear cache, play on old xbox. NOTHING WORKS.
This game sold so badly it will probably never be fixed too.
Oh any BTW Pony, what do you mean your saved game is corrupt? Did you only have the option of starting a new game? ITs just that I can replay previous levels just not 4-2 so I dont think my save is corrupted just the game is broken.