I have an ATI 4890 GPU and a HP 2509m moniter. I updated my ATI drivers and the display reset itself to a smaller physical size on my moniter screen. My desktop display (and any other display, such as the internet) is about 1 1/2 inches too small on each of my left and right sides. In addition, the top and bottom are about 1 inch too small.
I have checked my Cataylst Control Center and my windows 7 settings, all of which have the resolution set to 1920 x 1080 and set to landscape. I have adjusted them smaller then rebooted, then put them back and rebooted and nothing changes.