Over the last few days, there have been several instances where I have gone to enter a new answer, or edit an old one, and the editor toolbar (the one that shows the icons for links, pictures, quotes etc.) does not appear. I can get around most of this, except it makes it impossible to add or replace a picture. Eventually it seems to start working again.
I am using the latest version of Firefox.
And it may be a coincidence, but it seems when things are not working right, I also get the CAPTCHA prompt asking of I am human.
Seems to have something to do with MathJax and Firefox. Even when I am having problems with electronics.stackexchange, I have no problems with other sites which do not use MathJax. Also, Chrome seems to be work okay even with electronics.stackexchange and MathJax.
The reason I am singling out MathJax, is that when this problem shows up, at the bottom of the page while the site is loading it says "Looking up cdn.mathjax.org" for quite some time (like five seconds) before the site finally loads. And then any pages using MathJax do not render correctly (shows the two dollar signs at each end of the formula, instead of interpreting the text within them).