There's no problem using Internet Explorer, MS Edge, Chrome, or Firefox. The developer of the gadget downloaded Waterfox on his Mac and had no problem. He says I'm the only user reporting this problem. I'm surprised that Firefox works, given the problem exists (on my machine) only with Firefox variants. If I open IE or Edge (where it works), then it will work in my 3 browsers. After closing IE/Edge, it will work in my browsers for a short time, then stop working.
I've been using this gadget a long time, some of the browsers are up-to-date and some not, I don't think any of the profiles have been changed lately, and I haven't started using any new addons, etc., recently (and I have next to nothing in this regard anyway).
Any bright ideas (dim ones accepted too)/ guesses (good, bad, educated/not)?
Thanks for any help you can provide.