Advertisements Blocks of channels intermittantly (as often as once a week) disappear from my S3. "Channel not available" message appears during live TV or recording is blank. Most of the time it is HD channels but not always. The channels frequently come back on their own. TiVo tech support blames Cablevision. Cablevision came out and replaced both cards. 5 days later same problem. My TiVo HD doesn't have problem. Reseating the cards and/or rebooting will often resolve problem.