I’m running a dual-screen set-up and need the proprietary drivers because the standard ones won’t drive the second screen at full resolution.

After updating to 12.0.4.3, xserver/gdm/lightdm won’t load at all. So only console login is left.

It appears they’ve messed up your kernel module configuration by installing both an upstream Nvidia driver as well as one from the Ubuntu repositories.

Now the “userland” Xorg libraries don’t match the version of the kernel module and that’s what you’re seeing here in the Xorg error logs. I’ll describe the steps to take in order to get a graphical login again.

1. Uninstall the manually installed Nvidia driver. Refer to one of the many questions on this, e.g.

   How to uninstall manually installed Nvidia drivers?

2. Uninstall all possible Ubuntu’s Nvidia packages:

1. List and remove the Nvidia kernel modules still installed (if any) at this point:

Repeat this until you see no Nvidia modules anymore using dkms status.

1. Install from the repositories:

or if you need newer/recent versions:

1. Verify that the Nvidia kernel driver is build for your running kernel:

should produce e.g. nvidia-304-updates, 304.88, 3.2.0-52-generic-pae, i686: installed.

Reboot.