At the EXACT TIMES of restarts, the event log recorded all different kinds of things there. For example, on 2/10/16, at 11:23:47am, there were three warnings when the PC was started and that it shut itself down very briefly and turned back on again. The three warnings include one with just event data, and two programs "egisupate.exe" and "lsass.exe". However, each day it seems some different things were recorded in the log. For example, on 2/19/16, there were the following things that recorded in the event log when the PC had the same behavior (shut down itself and restart during starting): p2psvc, explorer.exe, CryptSvc, avastui.exe, RAVCpl64.exe, PNRPsvc; on 2/20/16, all data, no programs can be identified; on 2/21/16 (today) the following: aswSnx, eventlog, EapHost. In fact, the last one and some of the ones I listed above are actually Microsoft products, part of the operation system. I can not delete every program that showed on the event log, my PC would be dead now if I did so. I believe these are not the programs that CAUSED the problem, but just during the problem they were there being booted. Something else is causing the issue.
At the night of 2/10/16 when I shut my PC down, there were 14 updates to be installed. The process took several hours, till about the midnight. Since then I noticed that every night there were 1 of 1 updates to be installed. After 10 consecutive days(!) I decided to check about it. I found that there is this one "Important" update (KB3115858) that is sitting there waiting for installation, and was failed being installed numerous times. I tried all different ways to resolve the issue, including ran the Windows Update troubleshooter, manually install, temporarily stop/exit all antivirus/anti-malware and cleanup programs, but still cannot install this update (please see the attached update history). I think these are all related issues, the crashes, shutting down during starting, and now every time the PC is turned off it is trying to download the update, and when I turn the PC on the next morning, it tries to install/configure it, but always failed. They might be caused by the same problem in my PC, that is yet to be found.