Ubuntu keeps closing - VirtualBox Windows 10 Host

Hi;

Im fairly new to Ubuntu and Linux in general and am having trouble with my virtualbox setup. I have 4 vms installed:

• Kali Linux
• CentOS 7
• OpenSUSE
• Ubuntu

The other 3 work fine but for some reason Ubuntu tends to close when i change from full screen, or try to switch the display Ubuntu is displayed on (I have a laptop with 1 external monitor)

I have tried:

• Reinstalling Ubuntu
• Disabling 3D acceleration
• Reinstalling Oracle VirtualBox and Guest Additions

Im not sure where to go from here, so any help would be much appreciated!

Thanks in advance