I too has a LE40B620RWQXU Samsung TV about 2 years old, I an having the same issues as all of you, I contacted Samsung and their are not interested as i am out of warranty.
I was given the contact of a Samsung Dealer to come and inspect the TV but this is at a cost. I love my TV but i just fall out of love with Samsung products,I will also be telling my friends about the bad after sales Samsung offered.
Not happy!!
MAS
June 2012