Just installed Virtualbox 4.3.2 with Oracle Extensions on my Windows 7 Pro workstation.
Installed an eval copy of Windows 8.1 Eval Guest and enabled 3D Video Accelaration.
Discovered when I went full screen that the whole guest session would flicker black on some window event like clicking on what passes for the start button in Windows 8.1. Google Chrome would lose contact with the window manager and display “(Not Responding)” and I would have to kill it.
Shutdown and uncheck 3D accelaration in the video settings (2D was not checked either) and restart problem solved.