I've seen that once before on a sharp set. First thing to make sure, is if you are using component video (Green, Red, Blue cables), double check the red one didn't get cut, or come out. If you are using HDMI, or DVI, it is a failed internal board on the Set. If you're in warranty, call your local dealer. If not, TBH, it's possibly not worth the repair, dell via slickdeals has 46 sharp LCDs for under 600 bucks consistently. Get an estimate, my local shop charges 100 bucks for the service call alone.