Sony Bravia XBR-2 32-inch LCD with popping noise problem

2 nights ago when I was turning my TV off for the night I suddenly hear a consistent popping noise coming from the TV (it happened when I turned the cable box off and was about to turn the TV off).

The popping noise is constant and happens regardless of what channel is on. However, when I mute the TV the popping noise stops which led me to believe it was a problem with the TV's sound system.

The Sony tech-support representative (over the phone) diagnosed it further to a problem not with the TV but with the cable box/service because there were no popping sounds when I played a DVD on my Playstation 2 that is attached to the TV.

Has anyone heard of something like this where the cable box/service is causing popping sounds? And is this something I should be concerned about causing damage to the TV's speakers?

There is no problem with the picture.
Well I don't have a specific cable box. My Westinghouse flatscreen TV just started popping; I've had the TV since February, and it hasn't started until now. It doesn't matter for me what's playting. If I'm playing atape or DVD, it still makes the nouse when I turn it off. It does NOT pop, however, unless the TV has been on for a few minutes. If I turn the TV on after it cools off, and then turn it off again quickly, it will not pop. It's only when it's been on awhile and it's hot. Should the top of the set be as hot as it is?