I don't normally use Linux, so it's been an adventure trying to get Ubuntu configured on a persistent USB stick boot. Particularly using NVIDIA drivers, since that's what I need to test the OpenGL based volume renderer which is having the issue.
I managed to make it boot to a black screen by removing said NVIDIA drivers. :(
But I figured out that I can change the /boot/grub.cfg file following hints from another tutorial and just change 'quiet splash' to 'text' and it boots into the console. Now to see if I can install those nvidia drivers again.