Odd problem with Media Center

[RainPure]

I am running Vista Home Premium on a new computer with 3gb of memory. I have installed all available updates. I am using a Hauppauge WinTV-HVR 1600 TV card. My signal is generated by a rooftop antenna with a rotor and booster.

When I use the Hauppauge software i get a crisp clear signal on all channels; however, when I use Media Center software on some channels (including 1161 WUSF-D1 thru 1164 WUSF-D4) I get no audio or video signal, just a blank screen. Other channels work fine.

Any suggestions would be greatly appreciated.