Q: itunes says this computer is unauthorized, then says it's already authorized when I try to authorize it, HELP?

If iTunes repeatedly prompts you to authorize you(r) computer

I tried all that. It doesn't help. I purchased several songs on iTunes store and one of them just loops me with "you are not authorized" and then the prompt and then it says "You have already authorized this computer." I did the SC thing which is the only thing that applies to an Apple computer using Apple's system. And yes. The song was purchased with my iPhone with the only Apple ID I have, like I purchase almost all of them. So now what?