Ubuntu - Nvidia driver

1. download driver-installation file from nvidia.com

2. sudo stop gdm (in 12.04... no gdm service... 'sudo service lightdm stop')

3. automatically going to text mode

   after ctrl + alt + F1 to go to text-mode, then you can stop gdm.

4. sudo ./NVIDIA-Linux-x86_64-295.40.run (downloaded)

5. after installing

6. sudo start gdm

I faced the problem below, when I do re-boot after 5th-step.

"You do not appear to be using the NVIDIA X driver. Please edit your X configuration file 
    (just run `nvidia-xconfig` as root), and restart the X server. "

then I did "sudo nvidia-xconfig"..... I couldn't see the X-window again :-(

I had to re-install ubunto to see it again.