apt-get install update-glx

• Remove radeon module blacklisting in /etc/modprobe.d
• Blacklist fglrx driver.
• Delete (backup) /etc/X11/xorg.conf. In general config is not needed to normal work.

Problem:

# glxinfo
name of display: :0.0
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Segmentation fault

Remove fglrx drivers:

apt-get remove --purge fglrx-atieventsd fglrx-control fglrx-driver fglrx-modules-dkms fglrx-source glx-alternative-fglrx
apt-get remove --purge libfglrx:amd64 libfglrx:i386 libfglrx-amdxvba1:amd64 libfglrx-amdxvba1:i386 libgl1-fglrx-glx:amd64 libgl1-fglrx-glx:i386 libgl1-fglrx-glx-i386

apt-get remove --purge xserver-xorg-video-ati xserver-xorg-video-radeon
apt-get install xserver-xorg-video-radeon
apt-get install --reinstall libgl1-mesa-glx libgl1-mesa-dri xserver-xorg-core

http://wiki.cchtml.com/index.php/Ubuntu_Maverick_Installation_Guide#Removing_Catalyst.2Ffglrx