The following is what I learned through CUDA programming environment setup.
Read official documents/supports first
In other words,
Do not google trouble shooting posts (at least) until some trouble comes up.
To run the installing process, you have to stop the X server.
If the X server fails to start after reboot, (temporarily) edit boot option by adding 'nomodeset' option to the kernel parameter and re-install a suitable video driver.
This may happen after distribution upgrade (sudo apt-get dist-upgrade in Ubuntu).