graphic: 0.983
device: 0.815
semantic: 0.691
register: 0.610
user-level: 0.579
performance: 0.546
virtual: 0.504
risc-v: 0.459
mistranslation: 0.416
PID: 0.383
TCG: 0.369
boot: 0.368
arm: 0.366
permissions: 0.342
debug: 0.341
vnc: 0.330
ppc: 0.330
VMM: 0.284
assembly: 0.263
architecture: 0.247
files: 0.226
socket: 0.213
KVM: 0.184
network: 0.182
i386: 0.145
x86: 0.130
kernel: 0.100
hypervisor: 0.070
peripherals: 0.046

Graphic session freezes and logs out
Description of problem:
Graphic session freezes and logs out resetting user session. I've tried with both X and Wayland.
The session does not last longer than 10-15 mins while working with:
    VSCode
    Firefox browser (no more than 5 open tabs - nothing heavy)

If only using console, the problem does not seem occur, or maybe it takes longer, but haven't been able to reproduce it.
Steps to reproduce:
No steps. Just using common apps (vscode editor and ffox browser) for 10-15 mins causes the problem. Standard sites: gitlab, stacoverflow.
Additional information:
I used this configuration for +1 year without issues. I guess some updates to either Ubuntu or Lubuntu causes the problem.
I deleted the guest VM and started with a fresh new Lubuntu 20.04 LTS AS IS no exttra software and the problem persists.

Happy to provide any info you may require. I've looked around in the logs but couldnn't find anything useful.