Using "X -probeonly"

[Bjarne Wichmann Petersen]

Hi

I need to do some testing of my graphicscard and need the output 
from "X -probeonly". But X bails out before I get any usefull information:

X Window System Version 7.0.0
Release Date: 21 December 2005
X Protocol Version 11, Revision 0, Release 7.0
Build Operating System:Linux 2.6.15.7 i686
Current Operating System: Linux desktop 2.6.15-26-k7 #1 SMP PREEMPT Thu A
ug 3 03:40:32 UTC 2006 i686
Build Date: 16 March 2006
        Before reporting problems, check http://wiki.x.org
        to make sure that you have the latest version.
Module Loader present
Markers: (--) probed, (**) from config file, (==) default setting,
        (++) from command line, (!!) notice, (II) informational,
        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Thu Aug 31 13:36:13 2006
(==) Using config file: "/etc/X11/xorg.conf"
dlopen: /usr/lib/xorg/modules/extensions/libGLcore.so: undefined symbol:
__glXLastContext
(EE) Failed to load /usr/lib/xorg/modules/extensions/libGLcore.so
(EE) Failed to load module "GLcore" (loader failed, 7)
[And here it stops]

I don't understand why I get this error, since it's the default xorg.conf, 
which works perfectly and I don't see this error ind /var/log/Xorg.0.log.

Bjarne