I'm very sorry for any inconvenience this may have caused you. Unfortunately, this sounds like it may need servicing. Here's the thread where you can get details on setting that up: http://forums.cnet.com/7723-13973_102-542437/service-issues-click-here-for-help/
About every 30 - 45 minutes the sound quits. We turn tv off, then on , and will work again for a perAny suggestions.