I recently bought a Polaroid MP3 player. PMP180-4. I've hooked it up to the computer and added music. On the screen it shows the music and will play it on the screen, but once disconnected it says "disk empty." I have an iMac and an wondering if this device will even function with one. I also got one of these for my husband's birthday later this week, but that one will be going back unopened unless this is an easy fix. Cathy