I have tried the search but couldn't find anything. I have been having this problem for about the last month but have not been able to resolve it. I have a Series 3 with two Comcast cable cards. It has been working fine for almost 2 years but in the last month channels will randomly not tune. I can be watching something a the screen will go black, or I will try to change the channel and not be able to tune. I have had Comcast out twice and they replaced the cards and ran new cable to be sure the signal strength is strong. When I look at signal strength it shows me 0 and "No digital signal". The DVR diagnostics screen is showing signal lock=no. Usually I can restart the TiVo or wait and the channel will come back. It seems to happen to all channels randomly, but only a few channels at a time. I don't know what to do next. Can anyone please help me? Thanks in advance.