I have an iPad 2 (I had this issue with the iPad 1st gen. as well), and I'm having some playback issues on movies and TV shows purchased through iTunes. I've removed the movies/shows and re-synced, I'm using the cable that came with my iPad.
The issue is that when I'm watching a movie/show, the video will freeze, get very pixelated, and then pick back up anywhere from 15 seconds to 2 minutes later in the video. I had this issue with 2 of the first gen iPads (as stated above) and took those back to the store, however my iPad 2 was a prize from a contest and cannot be returned.
I'm sorry if this question has already been answered, but if anyone has any tips or answers about this that could help me out, it would be greatly appreciated.