I have had this happen and have seen many questions about this behavior, in this forum and elsewhere. I was fortunate enough to be able to find an answer after searching a lot, so I thought that I'd share the link. Scenario 3 was my problem. I try not to take credit for other people's work.
https://support.microsoft.com/en-us/help/2028504/windows-kernel-event-id-41-error-the-system-has-rebooted-without-clean
https://support.microsoft.com/en-us/help/2028504/windows-kernel-event-id-41-error-the-system-has-rebooted-without-clean