Impermanent Screen Resolution

Acer Aspire 2000 (Cl32) runs WinXP/Pro/Sp3 and can be set to display in its native resolution of 1280 x 800 from its ATI Mobility Radeon 9200 video card. However, when it reboots, it reverts to 640 x 480, and often blames an absent or corrupt video driver. My remedy is to UNinstall the video driver from Device Manager and reboot, but I'd like to have native resolution without going through this 'readjustment' at every reboot. On the rare occasions that I can access the ATI Control Panel, Schemes in the Display tab, is empty. If I select 'Default Single Display' from the offered options, the SAVE button is greyed out. Any suggestions as to how I can get the native resolution to 'stick' ?