Lightdm crashes on bootup after installing Virtualbox guest addition tools on Ubuntu Desktop 16.04.1 when 3D Acceleration is Enabled in the Virtualbox machine settings.

[Ian]

After a clean install of Ubuntu 16.04.1 on Virtualbox with 3D acceleration enabled on the Virtualbox VM settings, when I install the guest additions to it and reboot the lightdm display manager continually restarts and I'm left with a black screen and blinking underscore. Unchecking 3D Acceleration or uninstalling the guest addition tools in /opt and rebooting fixes the issue.

Virtualbox version: 5.1.4 r1110228
VBoxGuestAdditions-5.1.4

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: lightdm (not installed)
ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16
Uname: Linux 4.4.0-36-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Tue Sep 6 08:38:03 2016
InstallationDate: Installed on 2016-09-02 (3 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)

What I've tried for troubleshooting -

Removing .Xauthority
Verifying permissions on various lightdm system folders.
Upgrading virtualbox
Purging / uninstalling and reinstalling lightdm
dpkg-reconfigure lightdm

[Ian (vallamost)]

I unchecked 'Enable-3D acceleration' in the VM settings then I reinstalled Ubuntu 16.04.1 and installed the guest additions, rebooted, lightdm did not crash at start up.