I'm sorry to hear that you're having this issue.
If the unit is only 5 months old, it's likely still within warranty. I would recommend having it serviced. You would be able to set that up by calling 800-SAMSUNG.
Help! I am rewriting this article since I had written the wrong TV model in my initial post. I just bought this Samsung 50 inch plasma no more than 5 months ago and after about 25-30 mins of TV watching, my TV suddenly turns itself off, makes about 3 or 4 rapid "clicking" sounds (like on/off very quickly) and then turns itself on again. Once it's done it the first time, it then does it every 2 to 3 mins, non stop! The only thing I can do is shut the TV for about 15 mins before it starts doing it again after 25 mins. It seems to especially happen when I watch sports.
It was suggested that I try to tap gently on the area behind the bezel where the invisible buttons are to see if that was the problem but that doesn't do anything.
It's hard to believe that a tv that expensive could do something like that... Can someone please help? Your help would be greatly appreciated. thank you.