Ubuntu VM stuck on black screen with a white underscore, no apparent error

[samgris]

I'm new to forums, please be kind if I get something wrong.
I too cannot start my VM;
I've tried to solve this by looking around on the Internet, and although some things do change, the end result is always the same: black screen after boot.
If I just start the machine normally, I get the infamous 'Failed to send host log message' and end up with a dead black screen: this is the log file for a normal boot, somebody please help me

[scottgus1]

I get the infamous 'Failed to send host log message'

This message can be ignored. It's a bug in the Linux video driver for the VMSVGA video card.

I don't see anything wrong in the log, though it's not complete, since the VM window was not closed when the log was taken.

Ubuntu is known to go to black-screen when there is not enough disk space available to start the desktop environment. This happens on real PCs too. Web-search how to fix Ubuntu black-screen because of too little disk space, do what the web-search says to the VM, and please let us know what happened.