The driver's themselves seem fine, the way Ubuntu handles their installation seems quite error prone to me. Whether that's actually nvidia's fault or not I do not know.
The 'Restricted Drivers' manager doesn't seem to work in a way I would expect. Un-activating an active nvidia driver just left my machine in an unbootable state.
I recently upgraded my nvidia card so to start 'afresh' I did;
sudo apt-get purge nvidia-current
At this point the restricted drivers manager was empty, I thought the whole point was to show drivers you can
use and not just ones in use??
sudo apt-get install nvidia-current
This installed the driver and created a new basic xorg.conf.