Currently Being ModeratedMay 13, 2013 2:24 AM (in response to glenn.hoffmann)
As a test, on the iPod's Summary screen in iTunes, check the box for Enable disk use and Apply the change.
This setting keeps the iPod's "disk" continuously mounted by the system. When disk use is NOT enabled, iTunes mounts the iPod's disk when syncing and then immediately unmounts the disk. The disk is not mounted most of the time. If iTunes then has a problem mounting the disk when it needs to sync the iPod, perhaps that message would come up.
NOTE: When Enable disk use is ON, you need to "eject" the iPod (unmount its disk) before physically disconnecting it.