I picked up a Tivo HD from Circuit City last week and I have been fighting with CableCards ever since. Comcast hasn't been any help at all, so I was hoping that I could get some help from someone here. Here is my problem in a nutshell. With the CableCards installed, I can tune all my digital channels (including HD) correctly, but I can't see any of the analog channels. If I take the CableCards out and scan for channels, I can tune the analog and clear QAM channels correctly. As soon as I pop the CableCards back in, the analog channels go black. The Comcast techs are stumped, not that this is hard to do. The Conditional Access screens are showing "Subscribed" and "Valid", so the cards appear to be paired correctly and have the correct subscription information. Any suggestions would be greatly appreciated.