Rolling Line Across Screen? Ideas Why?

It's a classic symptom of a ground loop, 2 or more ground connections at a different potential. If the coax coming into the house isn't grounded, ground it to the main building ground and that usually solves the problem. Search the forum and the internet for all kinds of ground loop information especially if that is not the source of the different ground potential.

Ahhhh. That dish isn't grounded - that must be it!

Thanks, Pat.

The rolling lines could also be caused by interference from signals of other cables or signal sources. I had the rolling lines showing up on my component in recently and made the lines go away by just adjusting the path of the component cables. Your mileage may vary.

Well, that may be it too, then. The DVI cable, component for the DVD player and component for HD receiver are all running together to get to the projector.

Signal cables running together is not a problem. It's power cables running with signal cables that cause interference. Putting grounding blocks near where the coax enters the building and running a 10ga copper wire from the blocks to the main building ground will meet building code requirements and probably cure the ground loop.