I have a very similar problem and seems like the same kinda model as yours as well. I created a new and similar Discussion as the previous thread was closed and could not reply to it on March 5th, 2012.

White spots on the TV screen. Started with one, then two, and now multiplying. When I called the 800 -Samsung, they were kind enough to say that they will replace it the DMV chip free of charge, however, I will have to pay for the service person who will come out. They were suppose to call me within 48 hrs but its over 72 hrs and after not getting a call from them, I called back. Only to find out that the service dept received my ticket on the 7th and now I have to wait another 48 hrs before they call me back. But after seeing the post in the previous thread, I figured it would be very helpful if someone can help out, and I don't have any expenses out of my own pocket. Specially for something like this where the problem is for multiple units. Don't even know how much service center is going to charge.

Here is my information:
Transaction: 2111994933
Model Code: HLT5075SX/XXA
S/N: AHDY3CKPB04125L
Manufactured: Nov 2007