Get this! I have an original Mac Pro, with original video hardware, and when I upgraded iTunes to 8.1, I was locked out of all of my HD tv shows (that I have been watching regularly), with an HDCP authentication error. I have a Syncmaster T240 HDMI/DVI screen, as well... you would think it would work..
Has anyone else had this problem? I am running OS X 10.5.6...