I have a Sony FW computer, with ATI 3470. I'm using a generic HDMI cable to connect to my 46" Bravia KDK46S5100. When I set the screen resolution to 1280X720, the full screen shows, at that resolution. However when I up the resolution to 1920X1080, I get a black bar around the picture. The TV is not totally filled up. However, all the contents of the screen are there Anyone have any idea what might be going on?