https://bugs.freedesktop.org/show_bug.cgi?id=71516
--- Comment #16 from Elven Decker sailing@together.net --- Progress!!
Starting from the login screen, I press control-alt F2 to bring up a command line. Then I run startx. I don't get a window manager, but I can find my way to xterm and then work from the command line after X starts. glxgears looks normal - smooth and as quickly as I believe the 9550 can go. :) Opening firefox, CNN and youtube videos play smoothly.
From your comments, I believe I have sidestepped lightdm. I opened synaptic and
reinstalled lightdm and associated programs. I then minimized synaptic and now I know what the display manager does. That's OK, I'll be rebooting anyway.
Next steps? I believe there is /usr/lib and an /etc folders. Can I clean them out and do another re-install? Will the config files get regenerated?
Thanks