Assuming you have installed the Catalyst driver and have got to the black screen, forcibly reboot via power reset. Then hold down the Shift key when GRUB boots to make it display the menu. Select the recovery mode line and hit enter. It will eventually display the recovery menu. Arrow down the menu and select either netroot or root. Hit enter. When it displays the command prompt, try the following:
Originally Posted by hoxzyk
or after installing via the Hardware Driver manager make sure you enter the above command prefixed by sudo before rebooting. The -f flag means "force".
aticonfig --initial -f
Let it boot normally this time. If it works then good otherwise repeat the above process but instead of the aticonfig command you can get rid of the Catalyst driver via:
Then a reboot should get you back to square 1. From there you will need to let us know which particular ATI graphics card you have via lspci,
apt-get remove --purge fglrx*