I made a playlist called oldies 1 and a playlist called rock 1. I made the rock 1 playlist first and it worked fine. When I made the oldies 1 playlist, all the songs from the rock 1 playlist ended up on the oldies 1 playlist and the oldies songs too. I tried individually deleting the rock 1 songs from the oldies playlist but it completely emptied the folder. The playlists on the computer are completely separated but on the fuze the rock 1 songs end up on the oldies 1 playlist instead of the oldies.
Explain exactly how you created the playlists and maybe we can help.