Only see black screen when playing .tivo files in any player

Okay, I just received my ethernet adapter that I ended up ordering from Tivo yesterday. I connected it and after some configuration involving using two routers, I was able to use the Tivo (Series 2, just got it for Christmas, by the way) to view photos, listen to music and all that fun stuff.

Here's where the problem comes up: I can use Tivo Desktop (2.2) to access all of the recordings, and I've even managed to download a few, but when I go to play them, all I see is a black screen. No sound, no picture, the time and progress bar at the bottom will move, but that's it. I'm using Windows Media Player 10. I've even tried other players that have been suggested. I've tried various codecs including NVidia, as well as several others. I'm not sure what I'm doing wrong here and any help would be greatly appreciated.

Edited to add:
As it turns out, the particular shows I was transferring and trying to watch, weren't playing (go figure). I tried a different show and it worked out fine. Law and Order was the original show that still won't work actually, but after transferring The Tonight Show, it played just fine. I will post if any other problems arise, thanks to those who may have planned on contributing an answer.