To reset the iPod (press and hold Play and Menu for 10 seconds).
Resetting the iPod is similar to pushing the Reset switch on your Mac. It forces the iPod to restart and (ideally) get its little house in order.
If reset doesn't work, there's nothing else for it than to restore the iPod to its original factory state—meaning that all the data on it is removed. To restore the iPod, launch the most recent copy of iPod Software Updater, and click the Restore button in the resulting window.
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