I have a Samsung PN50B550-T2F (almost 2 years old) and for more than 2 months a thin (possibly one pixel thick) vertical line runs down the center of the screen whenever the television is on. This line has a redish tinge to it and is more visible on bright / white backgrounds and is almost invisible with darker backgrounds. If the screen has a dark bottom and a bright top, the vertical line will only be visible at the top half of the picture. I have run the picture test and that didn't fix it. Also the line is present on all inputs and with all sources (analog and digital) that I have tried. Additionally, after having the problem exist everyday for 2 months, it mysteriously went away last week. This autofix only lasted 2 days/uses, because the problem has since returned for an unknown reason. No physical damage has ever occurred to the tv. No water. No kids. No pets. Any ideas on what could cause this problem and what parts may be needed to fix the tv or how much a repair may cost? I'm hoping it is not the display panel as I have read that part is pricey. Thanks in advance for your response.