Is this line bleed or something else?

My LG PK540-UE has recently started showing this horizontal bar with line bleed. It sometimes is at the very top of the tv but the pictures i attached show this bar at the middle of the tv image. It sometimes goes away. If you unplug the tv for a couple of hours and then turn it back on the bar will still be there but will then disappear after about 15min. and wont show up again for the whole day until i turn the tv off overnight(off not unplugged) and then I turn it on in the morning. Once i turn it on in the morning, the bar is there and then wont ever go away because then the tv will shut itself off after being on for about 15-20min. The only way I can use the tv is to make sure and unplug it overnight and then turn it on and leave it on all day then and only then will the tv stay on and the bar will disappear. Any suggestions on what may be the culprit. I think that it is a power supply but I dont know which one.