Not enough space for DB music and must free space

I’m having the same problem, but I’ve got a Mac–any suggestions for me?  When I connect the Fuze to the computer, I have deleted all the files (audiobooks) that have shown up on the screen.  A check of all folders shows them as empty, but the same message (“delete 90mb”) keeps appearing.   I’m unable to get anything else to show on my Fuze screen.  I’ve tried both reformatting techniques and the darn thing just doesn’t.  Help?  Anyone?