I got home last night and my TiVo could not find a signal on any channel. Thinking it was a Comcast problem, I tried to play some recorded video. The recorded playback shows the status bar and seems to play, fast forward, etc., but just a blank screen for the actual video. This includes programs I've watched before and know are good.

I copied a file to another TiVo by MRV, and could watch it. I copied a show in the other direction, and could not watch it. The YouTube and Netflix apps were the same: I could navigate the menus and choose a video, but the video display was blank. Thinking that a bad cable card could somehow be corrupting thigns, I pulled it out and still could not watch recorded programs.

One other oddity: the HD menus all work as normal, but the SD menus have an all black background, instead of the usual blue.

All of this was with an HDMI cable. I tried a composite cable instead and got the same behavior, but didn't test as many scenarios.

I looked through old forum posts and saw a similar thread, and the suggestion was that the tuner had gone bad. I don't understand that, becasue I thought the tuner was only used for recording (which is why you can play a recorded program while recording on both tuners).

TiVo is sending me a replacement, but I'm still hoping to figure out what is going on. That's partly curiosity on my part, and partly that swaping in a new unit would take a lot of work and involve losing a bunch of recorded programming that I can't transfer becasue of copy-protection.

Any thoughts would be appreciated.