Dear William,
I have created an Ubuntu 20.04 VM and downloaded/installed the 3.0.1 (including updates) which was built on Ubuntu 16 .
I was not able to reproduce any crashes.
I haven`t installed any additional `guest support` on Ubuntu 20.04. Not sure what you need from the guest addition in particular, but I noticed both mouse pointer/ displays and sharing files are (for me) quite well supported in Vbox 6.1 without any additions (both for Ubuntu and CentOS VM).
Related to this, I have followed this https://www.if-not-true-then-false.com/2...-hat-rhel/
for installing Guest additions on CentOS VM, but I actually corrupted the VM! So I would not recommend.
Do you have any other Anaconda/Miniconda or Python installation in your machine? I wonder if there is some conflict.
Can I also ask you if you have the AutoBackup enabled from Preferences?