I solved that problem, at last!
Get and install a program called "yanc"
and change module options. Check "ali agp" and "force 2x agp speed", i think.
then /etc/modules.conf will get updated. Beware that any time that /etc/modules.conf gets changed, yanc's line might get erased, but the solution is to check again these options
AMD k6-2 400 Mhz
GeForce2 Mx 400