Chosen Solution
Why are there colored horizontal and vertical lines on my screen? The lines appear superimposed over signal picture whenever the TV is on. Vertical lines are multiple thin lines of different colors in approx 3 inch band. They intersect perpendicular to a band of thin gray horizontal lines just left of center screen.
D White without seeing what you see and only going by your description, it sounds like a bad tcon board, but it is possible that it is a broken LCD. To make further determination, consider posting some images of what your display looks like.
I think I had the same problem, but the pixels were rainbow-ish and only horizontal. All we did to fix it was unplug the tv and plug it back in!
