I'm sorry to hear you're having problems with your set. Unfortunately, the only recourse I can suggest is to call or contact the Samsung customer service center in your region to see what options are available for repair. They may be able to put you in contact with a repair center that is certified to repair Samsung televisions.
I purchased a Samsung 32" tube HD flat screen in Mexico for my condo in Puerto Vallarta (I know -- a HD flat screen tube set is a rare beast). It's been working fine for about three years. All of a sudden it has started to turn itself off. The screen goes blank and I hear the little "power off" jingle and it powers off. I start it again and it stays on for a while, but then does it again. The longer its on, the more frequent the occurrences until you get to a point where you turn it on, it immediately turns itself off. I'm guessing some component is getting hot. What's strange is that it doesn't just go dead, it actually powers itself off, so it appears as if the TV is controlling the power off. Any thoughts or suggestions would be appreciated. Being in Mexico, there aren't a whole lot of competent service centers available.