Microsoft KB3163018 appears to be the root cause of several users experiencing their windows 10 systems stuck ‘restarting’ for hours. I’ve seen this occur on several devices and I have never seen the system auto escape out of the problem. In every case I had to hard reboot the system to get it to come back online.
It appears we are not the only ones seeing this issue:
http://news.softpedia.com/news/microsoft-acknowledges-issues-with-windows-10-cumulative-update-kb3163018-505369.shtml
http://answers.microsoft.com/en-us/windows/forum/windows_10-update/kb3163018-will-not-install/b8376131-c9c4-4494-9a1f-2eb7709f1027?page=1
