Windows client just Aborted. How can I find out why?

[jm_paulin]

Right,

I am running 4.3.28 on Ubuntu 14.04.1. I have the extension installed.
Client is Windows 10 preview. The Guest Additions are installed.

I only noticed this failure when I put the windows client in full-screen. So basically what happen is like if the power plug was pulled off on the VM. It appears to be random, but it appear to be linked to some mouse/keyboard interaction. The windows log reports after reboot: Kernel-Power; "The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly." and "The previous system shutdown at 11:52:28 on ‎09/‎07/‎2015 was unexpected." There are no entries in the previous 45 min prior that.

The last few lines I see in the VBox.log are:

48:45:26.490536 UIMultiScreenLayout::update: GUI/AutomountGuestScreens is disabled.
48:45:26.490816 UIMachineLogic: Guest-screen count changed.
48:45:26.491003 UIFrameBufferQImage::resizeEvent: Format=843204434, BitsPerPixel=32, BytesPerLine=7680, Size=1920x1080
48:45:26.491010 UIFrameBufferQImage::resizeEvent: Resizing to directly use VGA device content..

Any ideas as where I could start from?

[mpack]

Zip the complete log and attach it here.

[jm_paulin]

Added the VBox.log....