I have been using a cablecard with my Hauppauge DCR-2650 digital tuner and Windows Media Center on my Windows 7 PC for 3 months with no problems on any of the Prime HD channels. I just subscribed to HBO and was not able to access any of the HBO channels, SD or HD. The message "Subscription Required" would appear after a few seconds, along with a message saying I needed to obtain a subscription to HBO. After Live Chatting to 3 techs over 3 days, I was finally able to access the HBO channels. I'm not sure this solution is permanent, but this is what I did. First I updated the firmware and drivers for my Hauppauge device. Then when I Live Chatted with the technician, he performed a "manual cablecard validation". During this process he asked for my cablecard ID, the Host ID, the Data ID and the activation code. He had me switch channels from an HBO channel to a non-HBO channel, then back again. Voila! It worked. So if my HBO disappears in the future I'll be asking for a tech who knows how to perform a "manual cablecard validation". Now I had my HBO channels in HD, but the picture was flickering a bit, enough to make it annoying to watch. After Googling "HBO HD flicker" I found that the problem was not with the cablecard or Fios, but with the graphics adapter settings. I have an integrated graphics chip on my PC, an Intel 3000 graphics chip. I opened the graphics properties page and in the "Media" category under "Image Enhancement Option" I turned off the "Adaptive Contrast Enhancement" feature. This fixed the flicker. Hopefully this post will help those few who are using a cablecard with their Home Theater PCs.