SUSE 10/10.1 have trouble with 21 inch monitors?

Hi, I just finished an install of SUSE 10.1 on a system with a 21 inch CRT. The CRT is a Hitachi Superscan 811. The video board used is a Matrox G400. The hardware was detected properly during the install. However, I only can get the equivalent of a 19-inch view area out of it. There is a 1-inch black border on the left and right, and a half-inch black border on the top and bottom of the display. I upgraded this system from Mandrake 9, where the display worked properly. I tried attaching the monitor to another system with SUSE 10.0 and a Voodoo 3dfx card, and still there are problems SUSE/Xorg to use the entire screen. I tried installing a driver from Matrox, but it had no effect. What is going on here? David