Did it just start happening after you've been using the set for awhile or is it new and happened immediately? If new and under warranty contact LG. If you've had it for awhile could be the HDMI cord. I had this problem and it turned out that one of my cats had been chewing on the cord. Simple replacement fixed it. If not that, it might be a board or one of the ribbon connections inside the set isn't seated correctly. If you're brave enough to remove the back, check the flat ribbons to see if one is loose. Go with warranty first if you've got one.My LG Plasma 50PC3D when turned on, starts to flash/flicker. There is no real video, just dark screen with flashes of different colors. Any ideas?