I followed this guide: Activate NVIDIA Graphics Card - Zorin Help to install the Nvidia driver instead of the Xorg driver for my old 8600 GS on my new Zorin OS Core 16. I clicked on the only Nvidia driver listed: nvidia-340 and pressed apply: there was a pk-client-error-quark error exit status 10 (313).
I tried to reboot to see if it works anyway, but now I have the "Oh no! Something has gone wrong" message at every boot.
Can you help me, please? If it is related to the Nvidia driver, is there a way to force the Xorg driver to go back?
Because it is an old card - you are better sticking with the Open Source nouveau driver that is part of the Linux kernel. Personally I have had no end of trouble using nVidia dedicated drivers when I used Zorin as my daily go to. The other issue is security as nVidia uses proprietary drivers.