How to revert back glx version from 1.4 to 1.2

[Ratin]

Hi its been known to many that Xorg versions supporting glx version
1.4 introduced some memory leak. My question is how do I roll back
only the GLX version back to 1.2? I am running ubuntu 9.10 which is
shipped with xserver 1.6.4 and x11-common version 7.4, nvidia driver
256.40,

 glxinfo shows;

name of display: :0.0
display: :0  screen: 0
direct rendering: Yes
server glx vendor string: NVIDIA Corporation
server glx version string: 1.4


Any help would be appreciated, thanks.

Ratin