Extreme screen flashing and guest unusable

[kekeke]

While this issue started on Windows 10 and I understand there are
problems there, I have since rebuilt the host machine from scratch
with Windows 8.1 and am still experiencing problems although they have
changed some. For the history of this issue please see: ​https://forums.virtualbox.org/viewtopic.php?f=6&t=69906&p=334049#p334049

Environment

VirtualBox 5.0.2 Latest extension pack installed Windows 8.1 host Ubuntu 14.04 guest

Current problem 1) When starting up the guest the guest window flashes. It is very extreme 2) On some starts when guest starts in full screen mode, the minibar is visible during startup but then is no
longer visible. 3) The guest periodically becomes unresponsive.
The screen looks perfectly normal but does not respond
to mouse clicks. I have assumed keyboard input as well but to
be completely accurate, I have not tested that. However, it does
seem that the UI has frozen. Nothing within the guest window responds
including the OS bar at the top of the Ubuntu window where you
can shut-down the OS. 4) The screen will be come black

• This is happening in fullscreen and normal view.

I have attached logs I marked this critical as I'm unable to use my dev environment
and get work done. I understand it may not be critical in your view. Sincerely, Karl

[kekeke]

A quick update: While I have been able to use the guest for the past 1/2 hour, it started with the minibar visible on both windows (2 monitor setup) but just now I wanted to minimize the guest and the minibar was only visible on one guest window.