Black Screen with mouse pointer after Switching on Xinerama and reboot

Hi,
I installed Zorin Pro16 ok, then went to nvidia settings and selected 'new x' then ticked xinerama. I save this to the etc/x11/conf file and restarted. After selecting zorin at the grub screen I ended up with two black screens and a white mouse pointer that I can move around, nothing else works.
Assuming xinerama is the culprit how do I revert to normal xscreen from this ?

Regards,
Russell

GDM conflicts with Xinerama. And that is why you are getting a blank screen instead of being greeted by the GDM Display Manager.
You can try booting into recovery menu by tapping the esc or tab key from the motherboard splash screen.
Advanced Options for Zorin
Then choose Recovery
Arrow key to enable Networking and enable it. Then back up to the recovery menu and arrow key down to the bottom to drop to prompt
Hit Enter
Then

sudo apt install lightdm

Follow the prompts, choosing to replace GDM with LightDM as your display manager. Once complete, back out of the menu to proceed to normal boot. This should enable you to Log in and use your desktop.

Thankyou for your response. I followed your instructions and I reached a purple 'ubuntu' looking screen with a login prompt, but after adding my password it returned to a black screen with a mouse pointer.

I think I might have to bite the bullet and re-install zorin and avoid xinerama.

Regards,
Russell

You might try removing the ~/.config/monitors.xml file via the terminal prompt in recovery, first.
See if that allows you to log in. The file will be recreated to Default state when you boot up and log in.