Unauthorized to access iTunes Radio

I have been going back and forth with Apple pretty much since the launch of iTunes radio on this issue and they don't seem to know what is causing it.

This only happens on certain stations, but when I click play, it will think for a second and then come up and say "We could not complete your iTunes Store Request. You are not authorized to access the requested resource"

Now, singing out and back in usually fixes the issue temporarily, but after listening to about 5 songs, it locks me out and gives me the same error.

Has anyone else had this? I am currently running the most recent versions of both OS X and iTunes, but this issue has carried across all versions.