I've tried several different things, well I guess the basics, I restarted iTunes, then restarted the whole computer, then I made sure my Firewall was off. I can't figure this out at all, by the way its an Apple TV 1.
Have you tried disconnecting and reconnecting the library? Use the Computers menu to disconnect the library in question, and then reconnect it. It'll require you to punch in a displayed auth code in iTunes again.