dri problem with an nvidia card

[Antoine JOLY]

I'm currently using the last version of the nvidia drivers (1.0-6111),
so I've commented the line load "dri", checked that the line "load glx"
exists. But when I try to launch UT 2004 for example, i get this
message : 
Xlib:  extension "XFree86-DRI" missing on display ":0.0".

and then te game tries to launch but crashes
I have the same message when I launch glxgears, but it works pretty good
and the performances are normal.
I have read perhaps the libgl from xfree may conflict with nvidia lib,
bit i don't think i can't remove it because it has very strong deps
Has someone any idea ?