I am using an Asus U35JC with a Nvidia GeForce 310 M graphics card.
System info says that my graphics card is unknown.
When I install any of two additional drivers and run sudo
nvidia-xconfig* and reboot, after grub it just stops loading the operating system. However, I can still login via tty1 and change /etc/X11/xorg.conf and restore the backup. (Before I figured this out I reinstalled Ubuntu every time.)
Thanks in advance to anyone who views this.
*: got the idea from: https://answers.launchpad.net/ubuntu/+source/xserver-xorg-video-nv/+question/163996