If you just like me, who manually installed the beta FGLRX package for ubuntu 12.10, you might face the same problem that I had when I upgrade my 12.10 kernel. After the required reboot, Gnome Shell (or whatever hardware accelerated DE you’re using) stopped working. The cause: The FGLRX package need to be recompiled using the new kernel. In my case, I had a blank screen, it didn’t even fall back to text mode.
First, we need to remove the old driver. Usually, this is a straight forward task. If your box boot to text mode, do the remove fglrx step immediately. If your box stopped at blank screen, reboot to recovery mode, then remove the package. Since Natty (11.04), Ubuntu will mount your root partition as read only, so you can’t make any change right away. In turn, we are presented with several options, such as boot to failsafe graphic, fix package, etc, etc. Unfortunately none of those option worked for me, as selecting any of them froze the system. To get Read Write, you need to select “drop to Root” and perform this on the shell:
root@Mach5-Nex:~# mount -o remount,rw /
Mount the rest of your fstab if you need to.
Next step is to remove the broken fglrx driver. If you install the .deb via dpkg, simply do this:
root@Mach5-Nex:~# apt-get remove fglrx*
If you installed the driver using GUI, do this:
root@Mach5-Nex:~# /usr/share/ati/fglrx-uninstall.sh –force
Reboot your system. If you’re lucky, the default opensource driver should kick in, and you are presented with your DE or its’ failsafe version. From here, you can reinstall the fglrx driver again.