[ON HOLD] Kubuntu 16.04 failing to boot

I’ve not long installed Kubuntu 16.04 on my new laptop and I am now unable to boot to either the desktop OR a Multi-Boot USB.

When I have the Multi-boot USB in, I see a warning flash up very quick which says ‘Could not open "\efi\boot\fallback’ then I get the GRUB Terminal screen with ‘grub>’

Without the Multi-boot USB in, it boot as normal then gets to the login screen where I enter my password then the screen goes blank/black with the mouse in the middle and that’s it, nothing else happens…

While I was reinstalling the Multi-boot USB I left the laptop. When I got back, the laptop had booted ok
I had recently added a ton of fonts so I removed them and rebooted, this must have helped as it booted fine.
I don’t know yet why booting with the USB created such a problem.
I’ll look into it further when I can.