I have a Panasonic plasma TV and DirecTivo (non-HD) and when I watch anything via DirecTv (including shows recorded on the DirecTivo) there are two grey bars slowly scrolling up the screen (its really noticeable in a dark scene, or when the screen fades black going to a commercial). It does not happen when I'm watching something via OTA HD channels nor via DVD. So, I assumed it was the S-Video cable I have running from the DirecTivo to the TV, so I replaced it with 3-pronged cables (yellow for video and red/white for audio...I forget what they're called)...but I still see the same bars. I thought for sure switching the cables would solve it buy now I'm confused.

Someone on another website had a similar problem and someone said it might be the "grounding cables"...what does that mean?

By the way, up until we moved one month ago I had this problem ANY time I watched something on FOX (via DirecTv). No other channels did it just FOX. But ever since we moved it happens during everything we watch via DirecTv.

What you see on the screen is sometimes referred to as 60 cycle hum. It is electrical interference you get from your power lines or them not being grounded properly. The traditional solution to this is to make sure that all of the components in your audio/video setup are plugged into the same outlet, thus ensuring that all grounds are at the same electrical potential (with exceptions of course, large system with a lot of power draw) Make sure that the outlet on the wall has 3 prongs on it and not just 2. And use a surge protector not matter what the size of the system, better to be safe than sorry.

What you read on the other site about the "grounding cables" is probably referring to the ground wire that runs attached to the coax line from the dish on the roof and comes down the side of your house.

The term is a "ground loop". Googling that will give you a lot of information.