I'm sorry I can't think of a more descriptive title while being succinct.

I'm running Ubuntu 18.04 with a windows 10 host, and everything was working relatively well. I wanted to be able to have a shared clipboard, so I followed online directions and used the device menu to insert the guest additions disk, followed the prompts, and restarted the VM.

Upon returning, the window had reduced to a very small size and I was having a lot of graphical glitches (windows only loading element-by-element when the mouse is hovered over them), and it was running insanely slow. I had visual memory up to maximum, tried lots of different graphical settings, no luck. I wanted to uninstall the guest additions and see if it at least went back to how it was, but then I had issues with mounting the disk and it wasnt working as expected. In a nutshell, everything seemed to be broken.

After hours of being incredibly frustrated and messing around I eventually gave up completely and deleted the whole VM. However, I know that my computer at work is in the exact same state, and I'd like to know how to fix it so that I don't have to start from scratch and reinstall everything (only for it to probably break again when I try and get shared clipboard working). Does anybody have any ideas?

  • to enable guest additions VT-d needs to be enabled on your CPU (you'll need to go into the BIOS configuration) and virtualbox needs to have 2D and 3D acceleration off in the configuration of that vm in virtualbox. While I believe what you're describing it is the opposite of the expected result. @fmo's answer will of uninstalling guest additions solves your immediate problem but I advise, for the long term that you attempt to meet the condtions for guest aditions to work and then reap the benefits of it working as intended.
    – tatsu
    Commented May 14, 2019 at 15:22

1 Answer 1


I would advise you uninstall Virtualbox guest aditions on that Ubuntu guest machine :

  1. open a terminal
  2. type :


cd /media/$USER/VBox_GAs_5.2.18/
sudo ./VBoxLinuxAdditions.run uninstall

optional steps : get guest additions actually working.

you need to enable Vt-D : https://software.intel.com/en-us/articles/step-by-step-guide-on-how-to-enable-intel-vt-d-and-perform-direct-device-assignment

also make sure 2-D and 3-D acceleration is off for that Virtual Machine

boot it up and type :

sudo apt install virtualbox-guest-x11

this will be tested to work with your version of the kernel.

  • if the .iso is still mounted (and it never unmounts unless you specifically eject it even after reboot) you can even run the uninstaller from the CD.
    – tatsu
    Commented May 14, 2019 at 15:19
  • The mounting also seemed to be broken - the CD wasn't working as expected (didn't show on the desktop or in /media even when mounted) Commented May 14, 2019 at 23:00
  • how do you know it's mounted though? where is it mounted to?
    – tatsu
    Commented May 15, 2019 at 7:03
  • It showed up in "disks" Commented May 15, 2019 at 10:45

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