I have a 2nd gen ipod nano. when I put music on my ipod and then try to find it through the 'artists' or 'songs' playlists, sometimes the artist or song title won't show up at all, even when I search for it. when I looked through my library and clicked get info for the songs that don't show up, it says that they have low complexity profiles, and the songs that work fine say things like 'MPEG-2, Layer 3' profiles. what causes this?