Ordinarily I ran Windows 10 as an admin. I had forgotten why. After the Wannacrypt thing, I decided to try Windows 10 as a user again. It was not pretty. The right-click menus kept getting corrupt - something to do with having different levels of scaling on different monitors apparently. Steam kept asking for credentials to update itself. Treesize Pro (registered) would not start, even in admin mode, even when explicitly run as an admin. The right-click menu option to run something as an administrator was absent from things which should have had it. Adobe Acrobat DC wouldn't work. Microsoft Edge insisted on handling PDFs, and I couldn't print them from Edge. I couldn't copy URLs from Edge either. Outlook 2013 didn't like connecting to my email accounts. And so on. Changing my account to a Power User account did not fix any of the issues. And so I reminded myself why I was running as an admin in the first place and I'm back to admin mode.