I installed the ATI catalyst driver a couple days ago and since then I haven't been able to see anything other than a boring purple screen when I try to log in. The boot splash has also been affected.
What should I do to get things back to normal?
I have had seemingly similar issues with Nvidia. Overscan, screen resolution issue, pushes menus beyond screen border.
Did you try loading the terminal app using keyboard shortcut once os loads? Try :~$ Ctr-Alt-T
If you see terminal screen show up then attempt running catalyst control centre by typing in terminal :~$ sudo amdcccle
One issue i currently have myself is that once resolution manually changed ( Nvidia chipset), after restart, xorg doesn't appear to be reading from the xorg.conf file. A manual change is required each time.