Virtualbox 5.0.20 - Linux Guest E_FAIL exception

I just upgraded my Virtualbox from 4x to 5.0.20 r106931 and my Linux guests won't start up in normal mode on Windows 7 64-bit host. It crashes with the following exception -

Failed to open a session for the virtual machine Lubuntu.

The VM session was aborted.

Result Code: E_FAIL (0x80004005)
Component: SessionMachine
Interface: ISession {7844aa05-b02e-4cdd-a04f-ade4a762e6b7}

However when I do a headless start and say show, I can get the Linux guests working.

I found via the official forums and other SU threads that this exception has been coming up from time to time through several versions of VirtualBox.

This is not a blocker for me but I am curious of this behavior. Can anyone shed light on it and of any possible fixes?