openSUSE 12.1 - display stuck zoomed in, truncates desktop edges

During (and after) installation of 12.1 from live cd, the display is zoomed in to the center. The edges of the display remain off-screen. You can move the mouse off-screen to select items or menus if you guess the location.

With my physical display settings turned to most narrow and short, about 5% is cut off from each side. At normal width, it is about 20%. I have never previously had this issue with other OS installations (windows, ubuntu, even opensuse 11.3). This cuts off 90% of the menu bars for the desktop and any running applications.

The physical display is model M221NV by Vizio. I have an older 1280x1024 display which does not exhibit this problem. When I switch to any standard (not wide) screen resolution on the problematic display, the edges are no longer cut off (not even the top and bottom, which have the same constraints as a wide screen resolution.)

I don’t know if there’s a way to configure the display in opensuse 12.1 beyond selecting pre-packaged resolutions. This is with a KDE installation, with an ATI Radeon 5750 and default installation drivers.

How should I troubleshoot this?

Thanks.