I'm sorry to hear that you're having this issue.
It may be the input board, but first, try checking the resolution on your cable/sat box to make sure that it's sending a HD signal through the component or HDMI output. If the problem was with the screen, the menu wouldn't come up clear, but also be pixelated.
If the box resolution doesn't help, you might want to have your unit inspected by a technician.
HELP! I have a 32" Samsung TV that developed what looks like large boxes of colored static/pixels on the screen while viewing any input. It is over the signal you are watching. I have tried all different types of inputs to the TV with the same results. This "static" or large boxes of pixels DO NOT show up on the menu screen though. I have reset the TV, dropped power for extended periods of time, tried different input signals with no luck. This all occurred within hours of Comcast hooking up their digital converter box to it. Any thoughts? I am leaning toward the input board.