Blank white screen attempting to play itunes purchased content

Allright, so yesterday I bought an Apple TV and attempted to get it working. I had many issues syncing, and received a number of message regarding port 3689 not being open. However, after I reset the Apple TV and did a factory reset, I managed to get some movies on it. They are movies that I converted myself, and they play fine. Besides the problems syncing (which I'm assuming will resurface), I am having trouble with my TV shows that I've purchased from itunes. When I go to play them on the Apple TV, they look like they are going to play, but all that shows up is a blank white screen. I haven't purchased any movies from itunes, so I cannot say for sure that it is all purchased content, or just TV shows. Is this problem related to my syncing issues? Or perhaps HDCP? I was under the impression that if my TV wasn't HDCP compliant, I would receive an error message. Not to mention that the TV IS HDCP compliant in the first place. I have a Mac Pro and an AirPort Extreme. The Mac Pro is connected to the AirPort via Ethernet, and I am currently creating an n-only wireless network at 5ghz (though I've tried it with other settings... it had the same issues).

I've been googling all night to try to find a fix, and it's getting pretty frustrating, so any help would be appreciated. Thanks!