Hello, I've just purchased an album with some 30 songs. Once downloaded I found out that most of the mp4 files ar corrupted because iTunes plays them up to a certain pont and then stops, passing to another song in the list. I tried playing the files, after revealing them in the Finder, with the quick look function, but the problem still stod there, so I assume it isn't an iTunes problem.
This forum is for questions from those managing sites on iTunes U, Apple's service for colleges and universities to post educational material in the iTunes Store. You'll be most likely to get help with this issue if you ask in the general iTunes forums.