The unit would be covered under warranty, so a repair may likely fix the problem. If that's cumbersome and not the answer, you might also consider contacting your retailer to see if an exchange is possible.
I want you to be happy with your purchase, and I'm sorry to hear that you're having this issue. But the problem is most likely fixable with a service call.
i've just purchased a samsung 50 inch series 5 550 plasma tv. I've had it for 1 week and its started emmiting a low crackling sound from the on board speakers. The sound is generally constant but deviates in pitch and tends to be more prominent when the tv's been on for a while. I have nothing connected to it besides a dvd player and an aerial cord. The sound doesn't change between switching between tv and dvd. Its a great tv picture wise but the sound is bloody annoying.