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/
I would have posted this in a thread I saw earlier, but I didn't know how to.
I have a Samsung HLS4676SX/XAA. I tried live chat but I can't seem to get any resolution. If I hook ANYTHING up to the TV I get this noise. I've tried to just use my Onkyo receiver and nix the internal speakers, but it seems like the TV has stopped outputting anything to the receiver as well. Any help would be greatly appreciated. The noise usually starts after the TV has been on about 10 minutes. I saw some talk of a reset using the "mute" sequence, but I have no idea what to do once I get into that menu. PLEASE HELP.