screen resolution problem



I'm running OSX 10.04 on a beige G3 with a Radeon card hooked up to a 19" optiquest monitor. There is no monitor hooked up to the onboard video. Everything works fine, except that I can't change my resolution, color depth or refresh rate. It is set on 1280x1024 currently with no other options and the color depth and refresh rate pop up menus are blank. The "show more resolutions" box is checked but disabled. I seem to remember that I was once able to switch resolutions but that the resolution I wanted wasn't recommended. I think now it's stuck on the unsupported one and won't let me switch back. I know that the display panel works properly because if I hook up the monitor to the onboard video everything works ok.

Is there anyway to reset the settings back to factory default or such? I looked for a display preferences file that I could trash but I couldn't find one.