Comcast service tech just left the house scratching his head. I lost the same 4 channels on both cable cards in my TivoHD. The channels work in my Comcast DVR. They tried taking down the cable cards and rebuilding both with out any luck. They appear in the guide and they are checked in the channel set up. I get the searching for signal on cable input when I go to any of the 4 channels. When I go and check the signal strength all 4 channels read zero. Tech is going to have some one higher up give me a call on Monday.