Samsung LE40R71B flickering problem
appears other people are having the same issue with Samsung TV's.
Try calling Samsung or wherever you bought it from.
I've been dealing with Samsung on this issue.
We got a 40" LCD in October 2010 and it started flickering January 2012.
Changing it from 'standard' to 'movie' helped (natural and dynamic flicker)
Then it started flickering in 'movie.'
I called Samsung and told them this issue is all over the internet. They agreed to pay for repair, parts and labor, even though it's out of warranty.
The guy just left and this is what I know. He said that in the 46" and larger, the issue is a jumper. In the 40" and, I think, smaller, it's the panel. He's ordering the panel and will be back to replace it when it comes in from the warehouse in CA.
Try calling Samsung and good luck!