I just upgraded from Ubuntu 17.04 to 17.10 and after the upgrade the screen flickers a white/grey colour about once a second. It seems to happen more when I move things on the screen. I am running inside VirtualBox. Everything worked fine before the upgrade.
This can be a factor of compositing
we can try to disable vsync in your VM by creating a file in /etc/profile.d
name it say script.sh
export vblank_mode = 0
then logout and login again
see if those white flicks will be gone