There are a few movies that my player just has a horrible time with. One is Rio and another is The Lorax. The stuttering video/audio isn't constant, but it seems to get worse during musical scenes, which generally have a lot going on visually as well as with the audio.
Even the previews on The Lorax disc had trouble playing, and there were extended black pauses in between.
Where it's only specific movies, is it likely a disc problem?
The player has the most recent firmware installed.