I have a very similar case with my set. I just noticed it the other night. Although on my set, the dark area is in the middle on the right hand side.
Hi all, I have a Samsung UN46D6000SFXZA, there has been a dark area along the top of the screen radiating toward the center of the screen for the last couple of months. I have not been able to find a similar instance of the problem on the internet, I was hoping someone here could help me identify the problem.