Sound issues I can't get the sound to work using an optical cable. It worked fine yesterday now not so much. I use the same cable for my hd tivo and the sound works great.

replace optical cable or re install toslink cable

With the TV remote you must select which signal input that you want to watch. You can have a TV cable, an HDMI plug, AV, and component, all connected at once and watch the one that you want to. After you select which ONE that you wish to see displayed on the screen, you will have to use the remote for that device

The TIVO system is not a problem. I have it and it works fine. Make sure all the cords are plugged and screwed in tight.

No there is not, You will just have to live with it working that way,

First if HD via component or HDMI the hookup or more likely the box if used is your issue---some sets will require a firmware update for certain boxes to work--I am guessing but guess you may be using HDMI.

This happened to me many times with my Sharp 40" LCD. I am actually running 2 tvs of of 1 HD Tivo. One in the bedroom with HDMI and then through the wall into my kitchen tv via Component. ( yes whatever is on in the bedroom plays in the kitchen).. So this AM my power dropped out for a few seconds then came back on. When the Tivo rebooted I got that " hdmi connection not permitted" message. In the past, I would just reboot everything and all would be ok.. But today I couldnt get the tv with the HDMI to display the programming. It would show the tivo menus, but when I tried to play anything or watch live tv, the message would pop up again. The kitchen TV with the components was working the whole time...
So finally I rebooted the Tivo one more time. But this time I left the HDMI cable unplugged from the Sharp in the bedroom untill the Tivo was fully booted and a live channel was playing in the kitchen. I then plugged the HDMI back into the bedroon TV, and it came back on. Im not saying this will work for you, But its worth a try

As far as I know, you need the cable cards to get HD through the Tivo, because they're what does the HD decoding and output.

Yes, the Tivo will just record in standard definition, instead of high def.

You can still hook the two up together, though.

What I would suggest (and have done in the past) is this:
Split the cable coming out of the cable box.
Hook one up to your HD cable box, and the other up to the Tivo.
Hook the output of your HD cable box to one HD input on your TV
Hook the output of your Tivo up to a different (non-HD) input on your TV.

This will allow you to watch HD while recording standard definition, and vise versa.

Running the HD through the Tivo will work, but will limit you to not be able to watch HD through it.

If you know that you do not have a cabling problem, then it sounds like a bad motherboard. If you have TiVo lifetime service, you should consider a flat-fee repair service such as the one here.

The solution I use is S-Video from cable box to TIVO, and from TIVO to TV. That gets you the highest quality signal that the TIVO can handle. To watch true HD signal, switch TV from S-Video input to Hi-Def input and tune to HD channel. I have an HD cable box connected to both outputs, your situation may be different.

Feel free to ask for more help.

Jeepster77