Could you check your home page address to make sure it isn't listed there? It would be after a vertical divider, for example:

https://www.mozilla.org/|about:preferences

I think you are familiar with where to check, but just in case: Startup, home page, tabs, and download settings.

Was it there? (Fingers crossed, because other possibilities seem very unlikely.)

Yes, since the Options page was opening constantly, it was EASY to find <smile>. I'm a bit embarrassed, because that level of checking should have been do-able for me, but thank you so much!!!

The vertical bar is a little subtle; it would be nice if there was a more easily readable way to list multiple tabs.

What's strange to me is yours is the third question today about this. I can't figure out why everyone is having this same problem at the same time. ???

Well, I certainly didn't save the Options page as a dual homepage, so perhaps it is resulting from some recent update. Thanks again.