I had the same issue, i installed fresh ubuntu, then updated all packages + dkms, then rebooted in fullscreen. Installed the Guest Additions while being in fullscreen mode, and rebooting in fullscreen...
I had the same issue, i installed fresh ubuntu, then updated all packages + dkms, then rebooted in fullscreen. Installed the Guest Additions while being in fullscreen mode, and rebooting in fullscreen...