Your post is more informative than any of the punks at the apple store and the email-only (!!!) itunes support they refered me to. Basically, my wife is having the same issue with her old library. She has an old @aol.com as the "user name". When I try to play one of these old songs (that I copied from her old laptop onto my desktop for a consolidated, shared library) I get that pop up, "This computer is not authorized to play "[song title]". Would you like to authorize it?" The 'Apple ID' auto populates with [heremail]@aol.com. You mentioned that you used your name and also your apple ID. What is the difference, and how can I enter it differently in the pop-up? I have tried manually typing in her (maiden) name, with and without a space, also the [heremail] without the @aol.com, then entering the password that we know of, and still nothing.
Sorry to bring up old issues, but I could really use the help. She has over 2000 purchased songs and they can't be played on anything but the ipod that hasn't been synced in years.
Also, when I log into her old iTunes account in the iTunes store, there are only about a dozen songs in the Purchased section. ***??? This makes me think there is a real issue with the iTunes system.
Like I said, apple was ZERO help with this. The emails that we received were sent to us by a person who probably bangs her head against brick walls for fun.
Also, I have set all the permissions to the folders and files so both her and my login have read/write.
Thanks in advance.