The other day, instead of syncing with my iTunes and iPhoto libraries like it usually does, my trusty old iPod 3G displayed a “required file in use” error.
I had been editing some audio tracks for a podcast site that I manage and had transferred them over to iTunes to turn into MP3’s. The error appeared, even though I had closed my audio editor prior to starting iTunes.
Undaunted, I closed all my open applications, including iTunes, then force quit the Finder. I then restarted iTunes without rebooting my computer. This time, my iPod synced normally without giving me an error message.