This is an old thread...but still helpful!

I am running 10.04 on a machine that has a NVIDIA video card. I tried installing the NVIDIA drivers but it didn't improve any visuals so I uninstalled minutes after. Apparently the file '/etc/X11/xorg.conf' was still step up to use the NVIDIA drivers, because upon reboot I got a flickering terminal login screen.

I saw what you said about the xorg.conf file and booted into recovery (hold left shift during boot to bring up the GRUB menu, and select recovery), started a root terminal and edited the 'xorg.conf' file changing "nvidia" to "nv", then rebooted.

Upon reboot Ubuntu complained about bad video driver config and I selected the "reset to default" options and rebooted again, success. No more flickering terminal login screen, just the normal GUI login.

Thanks for the post.