I should also have mentioned that when the problem disappeared after adding the hatnote, I removed the hatnote, thinking something else had changed. But the problem then returned. So I undid that edit, and the problem disappeared again.

I just read your 4:09 pm note. The test you describe is invalid. I told you that the links in the View history tab always work. The test you need to do is restore this old version: https://en.wikipedia.org/w/index.php?title=Convolution_theorem&oldid=963652013 as the current one, and then access it via https://en.wikipedia.org/wiki/Convolution_theorem. That version has the "bad" LaTex and no hatnote.

Also keep in mind the the same problem happened with two different PCs, two different versions of Windows, and two different browsers. So your conclusion of "a bug in some piece of software installed on that local machine" is not very likely. Until you try the test I just described, I don't think you have given it your best shot. I do realize it's a crazy-sounding problem, but I hope you will try a little harder. Thank you.

If the content of a website can crash a complete computer system, then the browser (or some software manipulating the browser, like so called "antivirus software") needs to be fixed. Not the website content itself. It really is as simple as that, sorry.

I understand your thinking. And the fact that adding a hatnote made the problem vanish is particularly unbelievable. But I spent a lot of time gathering clues for you, and restarting PCs, and all I ask is that you try a simple test, but not the one you did try. I could have told you that one would work... in fact I did.

The article is readable now, so I'm "good". I'm only here at the request of your own Volunteer Response Team, and trying to help you, not myself. And to get here, I had to go through a gauntlet of instructions emphasizing the importance of being meticulous and complete in describing the problem. That's what I did, and I expected you to also be meticulous and complete. Instead, you performed a test that I already knew would not reproduce the problem.

We're done now.

@Bob_K: I do not own any PC with a Microsoft Windows operating system, hence I will not be able to reproduce your local computer configuration. Even if I managed to reproduce the problem that wouldn't change much: the thing to fix is whatever piece of software creates that crash locally.
Furthermore, I'll stick to the statement that both PCs might have the same software installed (e.g. "CCleaner" which locally tampers with web browser's integrity).

If you prefer second opinions, https://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Computing might be a potential place to bring this up.

In T256148#6250141, @Bob_K wrote:

The test you need to do is restore this old version: https://en.wikipedia.org/w/index.php?title=Convolution_theorem&oldid=963652013 as the current one, and then access it via https://en.wikipedia.org/wiki/Convolution_theorem. That version has the "bad" LaTex and no hatnote.

I was unable to reproduce a browser freeze on Windows 10 Fx 77.0.1 64-bit with these instructions.

Thank you for the link, but I don't think I will pursue the problem any farther. And now that I have the full story, I have a helpful suggestion for you. It would have gone a long way if your initial response was something like:

"I cannot repeat exactly what Bob did, because I don't have access to a Windows PC, and there is nobody else I can hand this off to.  I did however try the experiment on my own equipment, and that does not reproduce the problem."

Thank you Izno. I am not particularly surprised; the whole incident felt like a bad 2-day long dream. But it's a simple test, so I think it was worth a try. And if someone else eventually has the same "dream", you won't be taken completely by surprise.