One of our hosts ran into a reboot loop after an unplanned shutdown(also known as powerloss). When booting again, the server went straight from booting to shutting down services and rebooting.
Windows update is often the problem when boot-problems occur in my experience. So, boot into recovery mode and command prompt, and remove the file C.WindowsWinSXSpending.xml.
Reboot the server and no updates messing with your host during boot.