Ubuntu 18.04 freezes after the start

I checked some of the other answers here, but they did not seem to solve my problem.

My special problem is that I start my virtual Ubuntu machine with Virtual Box and freeze after booting. I've turned off password login so it just stays on the desktop screen without me having to click or do anything.

I tried increasing the number of processors from 1 to 4 and enabling PAE / NX, but that did not work.

Just for a few extra background information, before I last shut down my computer, I spent a lot of time installing the SciPy libraries, as well as CUDA and cuDNN. In fact, I had some issues getting the GPU up and turning it off to run it later, only to find that the machine is now completely freezing.

Does anyone have suggestions on what to do and what is wrong?

Many Thanks.