Samsung PN50C550 single horizontal line

[YamahaFreak]

This TV has been working flawlessly for a few years now, ever since I got it secondhand and replaced the failed power supply. I turned it on today and there is suddenly a single pixel tall horizontal solid black line, almost exactly halfway up the panel, running all the way from edge to edge. It is consistent and does not move, flicker, or change color. I went inside and reseated all cables and connectors - no change. Ideas? Please don't tell me my panel is bad because I love this TV!