There's a whole thread about Comcast CableCARD issues:
Tivo troubleshooting document:
This should help you isolate the problem. Some quick info: there are three values in Conditional Access that matter a lot: Con:
should be yes (card is configured), Auth:
should be S or possibly FWK (card is authorized by the cable company), and Val:
should be V and not ? (the card is paired with your unit). I have the first two but not the last one. You have to badger Comcast techs, who will keep throwing you into a "let's compare pairing values" script that culminates in a tech to be sent out. You have to get them to send the proper "hit" to authorize your card.
I now have channels, but I still have Val: ?, meaning I'm not paired up with Comcast systems. I can't get them to resolve it, and I can get a replacement but I have working channels right now. If you have a Comcast depot nearby, you can go to them and try to get a replacement. It's tough to want to replace it and get one that's possibly worse, but that's what I should do. A tech will replace cards until he finds one that works, so it might be better since he'll have a few of 'em.