Television and Home Theater

My friends vcr pooped out on her last week, or so we thought. It rewinds, forwards, etc. Plays, but no picture...just sound. All you get is a blue screen. Thought it was bad so we got one from somebody else which I tried on my tv before trying it on hers. Basically it's just being used to watch tv programs that I have taped for her. She'd get through one episode and then it would go to the blank screen again. She'd stop it, take the tape out, put it back in, then play and it'd be fine again. Any idea what would cause this??? (Aside from her apartment being posessed) Please help.

Hello

 This just started 3 days ago. After being on for about 90 minutes, the TV starts emitting a very high-pitched whine -- only on non-HD channels. The whine goes away when the TV is tuned to an HD channel.

I think the TV is about 3 years old. I bought it used, as is, about a year ago from a lab that tested cable TV settop  boxes all day -- so it pretty much ran all day for a couple of years. However, no trouble up until this point.

Any ideas what the problem might be?

Thanks, Steve A 

I have an emerson tv. The lower channels jump up and down but the higher channels are fine. WHat would cause that? I have even taken the tv to someone elses house to make sure it wasnt my cabel and it does it there to. Someone PLEASE help