This allowed me to get Ubuntu running with the desktop
Turn off the option “Enable Nested Paging” in the VM configuration under Setting->System->Acceleration.
Run this on MAC to give full screen option
$ sudo defaults write /Applications/VirtualBox.app/Contents/Resources/vmstarter.app/Contents/Info.plist LSUIPresentationMode -int 4
$ sudo defaults write /Applications/VirtualBox.app/Contents/Resources/VirtualBoxVM.app/Contents/Info.plist LSUIPresentationMode -int 4
$ sudo chmod 644 /Applications/VirtualBox.app/Contents/Resources/VirtualBoxVM.app/Contents/Info.plist
$ sudo chmod 644 /Applications/VirtualBox.app/Contents/Resources/vmstarter.app/Contents/Info.plist