My Samsung 46" TV's picture just keeps flickering?

My 22 month old Samsung 46" TV's picture flickers constantly - like a strobe light effect - after approximately 30 mins of normal picture quality/viewing. If I switch it off and on again it makes no difference, however after teh TV has been on for approx 4hrs the flickering starts to abate, I have checked and cleaned all the connections to it etc but to no avail..........I'm losing the will to live here :-( Model no LE46C530F1W I also have a 32" Samsung which I have owned for approx 6 years with no problems whatsoever. Please help? :-)