How have you created playlists, did you create them in app for example in WMP as that would not be able to locate them on its own, if you tried to play them you would get error message and you would have to re point at ext drive but i worry you would have to do this for each track, depends what software you use i suppose im not that familar with many TBH and if you did get it to work then you would have to make sure that the ext drive was assigned the same drive letter every time it was connected