Trying to help straighten a friend's iTunes library. Before 2010, songs purchased on an AIM AppleID. After, a new GMail AppleID. She has passwords to all. When I doubleclick a Protected song, prompts to authorize, she puts in password, then says computer is already authorized. Doesn't play. Repeat over and over. Can log into store with that AppleID. Browse past purchases. But still can't play. Would like to convert to the newer unprotected so she can get merged into Match.