I followed the instructions at https://forums.virtualbox.org/viewtopic.php?f=3&t=87526#p418088
where I disabled "Wayland in /etc/gdm3/custom.conf by uncommenting 'WaylandEnable = False'." This seems to work around the issue. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1800294 Title: Xorg freeze black screen hang up To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1800294/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs