try nVidia''s newest reference drivers. If that doesn''t work I would remove the GeForce card completely from the system, uninstalling the drivers completely. Re-install the chipset drivers, AMD drivers, and the AGP drivers that should have come with your motherboard. Then re-install directx7a. You may have to wipe your hard drive and re-install windows to get everything. GeForce cards have serious problems with AMD chipsets (especially on Athlon boards) and soundblaster live cards. You have to have the right motherboard and follow an exact procedure to get them to work right with everything. You would also have to make numerous manual registry entries to get it to work like it should. My advice is forget about it. Some of the same problems occur with the TNT2 line of cards as well. I have tried an ASUS card and an Elsa card. The ASUS card was a complete pain in the ass, and the Elsa card was almost as bad. I ended up putting my Voodoo3 back in (not one weird thing/problem since then).

You might check your power supply as well. Athlons and GeForce cards need a LOT of power.

Good Luck

Somehow I never ran into problems when using ASUS Ultra Tnt2. Its gives a better frame rate than G400. Maybe because of the Bump Mapping. Yes Bumpmapping can be a severe load on the engine