A family of Microsoft word processing software products for creating web, email, and print documents.
1 year and 3 months after this problem struck (following an update), the problem has been solved!
I searched the registry for _auto_file and found a few entries, some with corruption indicators, like symbol characters and odd shapes for entry titles.
I deleted all and rebooted, without change. I then tried to do an online re-installation, which just hung. It did work in the past since the initial problem, but never solved it.
So I ran cccleaner (groan... :), which reported gads of errors, notable some with the .dotm and _auto_file. So I cleaned and repeated twice more, each time finding similar unlinked references, until no errors were found.
Reboot and another attempt at online reinstall and SUCCESS :-)))