sansa clip palylist files are useless
1. connect your sansa clip to your pc
2. make a playlist by right-clicking a track in your music folder and
selecting make playlist.
This creates a playlist that depends upon the numerical position of the track in the music folder.
As soon as you edit the contents of the music folder by adding or deleting other tracks, if the changes are earlier in the alphabet of the track name, the playlist will no longer refer to the correct track.