System doesn't boot after amd 11.9 driver install

I had all sorts of fun getting the 11.9 driver installed and working. Even using the "additional drivers" didn't work for me. I had the same issue you had as well. In the end I followed the following steps after booting into recovery and remounting, then dropping into netroot prompt:

1) Remove the fglrx and revert configuration:

    sudo sh /usr/share/ati/fglrx-uninstall.sh
    sudo apt-get remove --purge xorg-driver-fglrx fglrx*
    sudo apt-get install --reinstall libgl1-mesa-glx libgl1-mesa-dri
    sudo dpkg-reconfigure xserver-xorg

2) Follow the manual install guide:

    sudo apt-get install build-essential cdbs fakeroot dh-make debhelper debconf libstdc++6 dkms libqtgui4 wget execstack libelfg0 dh-modaliases
    sudo apt-get install ia32-libs (only if on amd64 as I was)
    sh ./ati-driver-installer-11-9-x86.x86_64.run (choose build deb packages)
    sudo dpkg -i fglrx*.deb
    sudo aticonfig --initial -f

3) Reboot.

On my Ubuntu 11.10 (Lenovo g770), I couldn't start the X (LightDM). I tried Catalyst 12.1 drivers. I got some errors about /usr/lib64.

So, I created a symlink and it worked.

ln -s /usr/lib /usr/lib64