My computer has an AMD Radeon HD6890 graphics card, and when Precise was running I had installed the proprietary drivers from AMD's website. After I updated to Quantal, Ubuntu would not detect my monitor's correct resolution, among other things. I went back on AMD's website to see if there were updated drivers and found some. Then I uninstalled the old drivers (which seemed to fix the resolution issue, but prevented Unity from running properly since the dock was no longer displayed). I installed the new drivers, following the instructions on this page: http://wiki.cchtml.com/index.php/Ubuntu. After rebooting, before I reached the login screen I get stuck at a terminal window that I can't type in. Not really skilled with linux enough to know what to do next at this point. Any help would be appreciated.