You are running kubuntu - that's KDE.
You need to stop X before installing the NVIDIA driver.
You can easily do it like this (no reboots needed):
<CTRL><ALT><F2> to get a terminal
login as yourself
Become root:
Backup your
xorg.conf in case of trouble:
Code:
cp /etc/X11/xorg.conf /etc/X11/xorg.conf.bak
Stop X:
Code:
/etc/init.d/kdm stop
-or, if you were running gnome-
Code:
/etc/init.d/gdm stop
If your root terminal disappears, switch back to it with <CTRL><ALT><F2>
Install the NVIDIA driver:
Code:
sh /path/to/NVIDIA-Linux-x86-X.Y.Z-pkg1.run
Answer the questions, accept the licence etc.
Then restart X:
Code:
/etc/init.d/kdm start
-or, if you were running gnome-
Code:
/etc/init.d/gdm start
Your primary graphical login (X) is on terminal <CTRL><ALT><F7>
If the install failed for some reason and you have lost your graphical login, you can go back to where you started like this:
Go back to the root terminal:
<CTRL><ALT><F2>
Restore x
org.conf:
Code:
cp /etc/X11/xorg.conf.bak /etc/X11/xorg.conf
Restart X:
Code:
/etc/init.d/kdm restart
But maybe you have already fixed this?
Edit:
Note: The 'buntus are unusual in that they run their GUI in runlevel 2 (init 2), single-user (no X) is runlevel 1 (init 1)