Note:
1. Instructions given below are only for Intel motherboards.
2. Instructions for other motherboards may be different.
3. Instructions for Asrock motherboards can be found in the link below. (Note: The instructions in the website are given for Windows 8, however the same instructions work for Windows 10 as well)
http://www.tech-recipes.com/rx/26800/windows-8-on-virtualbox-and-vmware-your-pc-needs-to-restart-fix/
1. Reboot your computer and enter the "BIOS mode" using whatever key your computer uses to get into that mode. Normally, F2 key is used.
2. In BIOS mode, enable "Virtualization Technology" in any one of the tabs in the BIOS screen.
3. Save and exit the BIOS mode and start the computer.
4. Now your VirtualBox should run Windows 10 without any problems.