Sharp Aquos LC52D92U suddenly developed bad jitter

I have a Sharp Aquos LC52D92U that is just over 4 years old. All of a sudden this morning, it has a pretty bad jitter, and I've tried 3 different inputs (DirecTV and Xbox360 via HDMI, DVD via component cables) and it happens on all of them so it must be the TV not the inputs. Anything I can look at or try? Is this likely to be repairable?