Ok, as sugested in another forum, in synaptic I marked all installed packages with 'Nvidia' in the name for removal, then ran
sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak
restarted with the following errors
when running 'hardware drivers' the list is empty and says "No Proprietary drivers are in use on this system."
Current dmesg output is at http://paste.ubuntu.com/144373/