A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Quick Repair solved my problem.
The real question is why there is a problem in the first place; that is, why is Microsoft installing defective software, and letting the user community solve the problem for them?
I installed Office 365 on July 30, and had to "repair" it on July 31.
With any other product, that would be unacceptable, but Microsoft seems quite comfortable with it.
Incidentally, I contacted Office 365 Tech Support about this issue. Their idea of tech support was to give me a link to this page (which I had already seen...as well as dozens of other pages on other forums.)
It's an interesting business model, isn't it? Release defective products and count on the buyers to provide solutions. I can see that it would be far cheaper than getting it right.