I too have had this problem with the very same model, it is most often improperly diagnosed as a t-con board issue by most who just want to provide an answer for the sake of there own ego at various forums. This is a manufacturing defect. I have been dealing with Samsung for over a month now and have been offered a replacement model of lesser quality(LN40C650L1F) at a prorated cost of $300.00 to me which I have not accepted as of yet. My TV began having this issue almost exactly 1 year beyond warranty period. Typically it will only happen when TV is cold(if temp in room falls to approx. 68 deg or lower). When cold due to naturally occurring shrinkage as with anything, the tab bonding contacts to the screen are broken and therefore gives you 3 thin horizontal lines across separating the screen into four quadrants vertically and blurry details of everything including channel info, menu info, etc. It goes away after several minutes of warm up time, as the unit warms up expansion of the panel resumes and contact through the defective tab bond is made and picture is back to normal. A quick test to determine this is if you gently squeeze the bezel(frame) around the panel at the top left corner approx. 2 to 4 inches from the corner(this is where the defective tab is located for this particular problem) the problem will go away until the unit is turned off and has ample time to cool off again. When you squeeze you are effectively forcing the tab bonding back together and contact again is made. Another way to diagnose would be to turn your thermostat in house up above 72 degrees or so and wait a few hours for the TV to acclimate to the temp(expand) .This is why if left alone for a few minutes to warm up the problem disappears. Consequently people who keep there homes on the warm side, say above 70 deg. don't often see this problem, but the more heat-cool cycles the units go through the more likely this problem will rear up its ugly head.I believe this defect will pop up eventually on all samsungs produced with the same tab bonding method or materials that were used for however long they were manufactured that way. Naturally everything moves(expands and contracts) through heat-cool cycles but proper engineering methods or materials should prevent something like this from happening for at least, lets say 10 years, the average life expectancy one would expect to get out of a $1500.00 or more purchase depending on screen size. Common sense would dictate larger screens would be more prone to this problem due to more movement and smaller less prone. Unfortunately there are numerous tab bonds all across the top of the screen(panel) and different ones affect different functions of the operation of the set, therefore there may be many other various problems people may be experiencing with there samsungs due to a failure of one of these tab bonds. They are often erroneously diagnosed as circuit board failures due to laziness on the part of the tech. I would recommend to anyone experiencing intermittent or any problems to gently squeeze all along the top of the bezel to locate a defective tab bond. As for dealing with Samsung, all I can say is good luck, it is difficult to reach their corporate office and even more difficult to get a resolution. I would gladly join in any class action lawsuit if brought about as the one regarding their capacitor issue disappeared once they sought to start addressing the issue and this was only after an absurd amount of complaints to the NJ BBB and consumer affairs websites. I think they realize that they have a huge problem with most models manufactured in the last 3-4 years(primarily due to using cheaper components as a cost reduction/profit boosting solution) and as with any large corp., are not willing to issue any recall as it is cheaper to just deal with angry customers on a case by case basis, very unfortunate for them as their sales will suffer terribly because most people research on the web before making major purchases in today,s world and thank god for that.