I am using Windows over a virtual machine run by VirtualBox. For no clear reason and on some of my computers only, the virtual machine suddenly wouldn’t want to start and systematically made the computer crash.

Description of the issue:

Host: xUbuntu 16.04 LTS

Client: Windows 7

VirtualBox version: 5.0.40

It finally appears that using the last version of Oracle VirtualBox solved the issue (with no change in the client or the host):

1. the first step consists in removing the old version of VirtualBox:

   sudo apt autoremove --purge virtualbox
   

2. then, edit the file /etc/apt/sources.list and insert the following lines:

   deb http://download.virtualbox.org/virtualbox/debian xenial contrib
   

3. finally, the new version of VirtualBox is installed with

   sudo apt update
   sudo apt install virtualbox-5.2
   

The virtual machine should work from scratch or with some minor tweaking on the configuration on the new VirtualBox.