Finally managed to resolve this (with help from the Ubuntu Launchpad folks) by setting noapic/nolapic/nomodeset in /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="noapic nolapic nomodeset splash quiet"

Had to carry out the following:

sudo nano /etc/default/grub

Ctrl+O to save

Ctrl+X to exit

Then run:

sudo update-grub2

I think that the one that actually made the difference was the nomodeset. Hope that helps someone out there experiencing the same issues.