I have a TIVO HD running for 3+ years, with a comcast (motorola) mutli stream cable card. It has been great running all this time with no issues. I noticed a few days ago that channel 824 (FX HD) is not working (black screen). Channel 823 and 825 are fine. It seems to be only this channel. This channel is fine on the comcast cable box in another room. I did a chat online with comcast and they "resent" the signal, but it did not fix the issue. Any ideas what can fix this issue?