Help! Why is my Sharp TV making noise and losing sound?

Recently I purchased a new HDTV and when I turned it on there was a loud ticking sound and the sound was distorted. Sometimes there would be no sound whatsoever. I returned the new TV for other reasons. When I watched my old TV the ticking sound was loud (just as it was with the new one), but I could play my DVD and my Tivo without a problem. If I transferred a program from my other Tivo or, if the program was recorded when the ticking had stopped, most of the time I could watch that program without any distortion. Then, I found that if I turned the cable box off I could watch my Tivo and play the DVD without any ticking or anything. They even installed a brand new cable box and as soon as the cable guy left the same thing happened, so it just cannot be the cable box. So, what is going on with Satellite service? I have DirecTV, but I'm beginning to think its not the DirecTV. Could it be the coax or other wires? What troubleshooting should I do? It can't be the outlet, because the other components work just fine. Help! I am baffled and I have a brand new Sharp LED LCD I want to hook up ASAP.