nvidia drivers fail completely after update to 3.5.019

It appears you'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 suggest you to take the steps below in order to revert to the ones provided by Ubuntu.

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:

   sudo apt-get purge 'nvidia-*'
   

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

   dkms status
   dkms remove nvidia -k your-kernel-version-here
   

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

4. Install from the repositories:

   sudo apt-get install nvidia-current nvidia-settings
   

   or if you need newer/recent versions:

   sudo apt-get install nvidia-current-updates nvidia-settings-updates
   

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

   dkms status | grep `uname -r`
   

   should produce e.g. nvidia-current, 313.09, 3.8.3-030803-generic, x86_64: installed.

6. Reboot.