iTunes authorization on an older iMac.

I am attempting to authorize an iMac G4 in iTunes so I can use it to play my iTunes music collection. When I attempt to authorize the computer or even sign in to my account, it returns a message saying “We could not complete your iTunes Store request. An unknown error has occurred. (-9836).”

The iMac is connected to the internet. I am using iTunes 8.

Any thoughts or guidance would be appreciated. Thank you.