every time i plug my shuffle in and try to put songs on, a window opens up saying 'could not find requiered disc' or something like that. i had songs on from the same copmuter but i restored the ipod and unistalled the version of itunes i had and installed itunes again. anything i can do? i tried diffrent versions of itunes but i can only use the latest that was installed. theres no songs on the ipod shuffle because it was restored but i think that might be why it doesnt work? y do i need a disc for a ipod shuffle?