This is a repost of my post of a couple of days ago.
I am running Ubuntu 18.04 and VB 6.0.8 on a Xeon system, lots of processors and memory.
I wanted a guest VM also with Ubuntu 18.04 on it (I'm running a package which brings in all sorts of stuff I don't want on my host system).
I install 18.04 and it all works fine. I then apply the current updates without making any changes and when I do this the guest VM breaks - I don't get a login screen when it boots (I never set it up to do automatic login).
It's probably Ubuntu who have broken something but I'd be grateful if people could point out any errors on my part.
A log file of it being booted and then my powering off is attached.