Ipod classic syncs with itunes, but when I disconnect, no music shows on ipod

I have an iPod classic 160GB and am able to sync the ipod to my macbook with iTunes 11, and it shows that I have 35gb of music on the iPod in iTunes. But when I disconnect the ipod, it says there is no music on the ipod. I think the problem started when I tried to connect the ipod to someone else's computer, but then there was a power outage so the computer died while the ipod was connected. Next thing I know, there is now music on the ipod. I've tried erasing everything and going back to factory settings, then re-syncing with my computer. Once the sync is complete, on the computer it shows the music is loaded, just when it's disconnected, there's nothing there.

Any help would be appreciated.

Thanks,
johnfitzk964