I'd be surprised if it was a tag problem, as I'm pretty sure that all I've done is to move around a couple of playlists and manually create a couple of new ones; I certainly haven't uploaded any new music.

I might have a go deleting the playlist that jEmplode is trying to update in emplode and see if that helps. For the record, jEmplode is trying to update that manually created playlist and the root Playlist playlist.

Ross