Flashing Screen on Bravia KDL-46XBR2 LCD

Screen has intermittent flashing of picture. Flat screen is two years old. When we first bought it, this problem appeared and before it got really bad, the flashing stopped.
As of yesterday, the television started flashing again. We checked all the wires to be sure if there was a lose connection. The flashing occurs on all channels. We have Time Warner cable hooked up with a DVD player.
We have our televison mounted on the wall.