Neither. I'm guessing that there's just a track you've uploaded that's somehow corrupted. Bad frame data or some such. All you need to do is figure out which one it is and delete it.

Think... Did you put any new tunes on the player just before the problem happened the first time?

Usually when this happens, it's a pirated tune you got from one of those file swapping services. This hardly ever happens with tunes you've ripped yourself. It's one of the many reasons I prefer to rip my own songs from my own CDs whereever possible.