Vizio Sound Problem

Question

I bought a new 42" Vizio. I connected using component cables and audio cables directly from my HD Cable box. No surround sound is being used.

The sound was fine for about 4 hours and then it started cracklin. This was on every channel and at every volume. Being that the TV was four house old I returned the TV and brought a new one home.

The new TV has run for about two weeks. Now the problem has returned. The speakers crackle on all channels and at every volume. It doesn't matter if the TV has been on for 30 seconds or 5 hours.

Is it possible for the problem to be with the cable box? Or just bad luck with two bad TVs? Right now I am not interested in buying a surround sound system.