Have an m320 using with Itunes on a mac book.  I was able to convert songs to mp3 and then just drag them into the m320 while connected via usb.  now I want to delete and add different songs, but when I deleted a bunch of songs, they don't show up on the player but the player is still indicating that the memory is full and I can't add any new songs.  I've only got 5 songs on it but it says it's as full as if I had 40 or so.  any ideas?  thanks.