So within 3-4 days I updated from Ubuntu 12.04 through 12.10 to 13.04 (on non-dev release). I have an onboard ATI X1250 which works fine with standard/Open Source drivers, but I really want to use my (now unplugged) HD6750.
Before updating I tested both on 13.04 Live USB and they worked flawlessly, but now in my updated System, the HD6xxx gives me the purple screen on startup two times, but only orange vertical lines once I reach Login. Even Ctrl-Alt-F2 gives me a black screen. What could need resetting/reconfiguring to get rid of any hidden settings left from the updating to have a startup akin to Live USB? Any other pointers? Might I have to do a clean install? Thanks for the help.
P.S. I have now tried reinstall (not fresh install) from Live USB, but to no avail.