"The upgrade failed on the video completely-- it installed a
newer kernel and the correct binary Nvidia driver, but it did not
install the kernel headers. So instead of falling back to some
lower-quality 2D video, it barfed completely and booted to the
console. No X at all. Which for a gnarly old Linux geek is no big
deal-- it booted, I can enter commands and fix it. Still, how hard
is it to make kernel headers a dependency of the driver, or to have
some kind of graceful failure? Why am I still fighting this same
old battle?
"I didn't feel like wasting a day messing with it, so I edited
xorg.conf manually to use the 2D nv driver and booted to an older,
known-good kernel. Did a fast Google and learned about Envy-ng.
Installed it, ran it, and in mere minutes dumb old Nvidia was
fixed. The Kubuntu restricted drivers manager was useless and
helpless, so hurrah and thank you for Envy-ng."