unable to authorize computer to listen to my music library

I normally play music from my iPad or iPhone, so there's no telling how long this has been an issue.

The issue seems to only affect library items I uploaded many years ago. I am able to listen to the music using my iPad or iPhome without an issue.

When I attempt to authorize my machine, I receive the error message "You cannot authorize more than 5 computers." "You have already authorized 5 computers with this Apple ID..."

When I attempt to "Deauthorize All" of my machines as per the instructions, I see the following message:

"One machine is authorized to play content purchased with this account." is displayed, therefore I don't have the ability to unauthorize machines attached to my account.

Needless to say, I'm stuck in a loop that I cannot get out of. Any ideas?