cd into the directory that VirtualBox is installed in and run this:
.\VBoxManage modifyvm your-vm-name --nested-hw-virt on
I also had to do the following:
- Go to Windows Control Panel (you can find it in the search box lower left side next to start button – type Control Panel)
- pick Programs and Features
- pick Windows Features in the left pane
- turn off HyperVisor (Microsoft’s Hypervisor conflicts with VirtualBox)
- run this at command prompt: bcdedit /set hypervisorlaunchtype off
- turn off windows feature “Virtual Machine Platform” if it is on
- reboot
BTW, Installing Docker for Windows 10 – requires turning on “Virtual Machine Platform” which will prohibit VirtualBox from running.