Have you tried seeing if this happens with all video inputs or just the TIVO? For example, is this happening with your DVD player as well? This would help you figure out if it is the TV or the TIVO.
If it is happening only with the TIVO, you might try seeing if it is happneing with all outputs of the TIVO (coax, RCA, s-video) or just with the outputs you currently have hooked up.
Hope that this helps.
I have a three year old Sony TV and have had Direct TV for two years. It has worked well with good picture quality until recently when very annoying wavy white lines have appeared on the screen. I can think of nothing that has changed that could cause this: I live in San Francisco where the weather is mild; the dish is on our roof (hard to get to). I have powered down and restarted, tried turning appliances on and off, changed the polarity of the plugs, installed Monster Cables, moved the TV around on it's swivel bas,but nothing seems to help. The Direct TV hardware says DVR R10 on the front; it is a year old, and is a unit that has built in TIVO. Any suggestions?