@Claude34 - THANKS! Great tip. I had been trying to get a decent answer from iTunes Support for as long as you, aand every answer started with, "X referred your problem to me..." Every day there was a new person "handling" the problem.
I only had to delete the Apple cookies, not all of them. First I deleted the iTunes cookie and left the security checks, but that did nothing (restarted both). Then I deleted the Apple cookies AND unchecked everything. After restarting the two apps it worked. Then I turned the security back on and it still works. That makes me think it was the Apple cookies.
Anybody out there who hasn't done this yet, check the dates on your cookies and send them in to iTunes support. They'll probably figure out which one is causing the problem, and maybe even send out an updated set for 9.2/10.4 user (Ha ha ha ha ha ha!).