In case anyone has not noticed yet, there is also a big problem with this very forum program.

When I made my original post, I included a screenshot. But that screenshot got ignored when I hit the submit button.

Now, Dropa is requesting the screenshot, because this forum program ignored my screenshot.

I've noticed one other poster saying they too had to re-upload their screenshots.

Can we get this forum program fixed, please?

The problem with screenshots is a vexed one and is being worked on.

https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_the-problem-does-not-happen-in-troubleshoot-mode If the problem does not happen in Troubleshoot Mode, the most likely cause is an extension, theme or hardware acceleration. See this article for solutions:

https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems (also deals with hardware acceleration)

Thank you for the screenshot. I'm attaching one showing the text I see. It's one thing if it's the wrong color, but in the two buttons top right, the space the text would use next to the icons is missing. Strange.

One thing disabled by Troubleshoot Mode, other than add-ons, is hardware acceleration of graphics. It would be a strange scenario that this is causing the problem, but you can disable it separately as a test. This article describes where to make that change: Firefox's performance settings. This will take effect the next time you exit Firefox and start it up again.

Last but possibly not least, two other things disabled are the optional userChrome.css and userContent.css files. Do you use any custom style rule files?

Thanks for your help, jscher2000.

I disabled the hardware acceleration. The text is still absent.

I've never heard of "userChrome.css and userContent.css files" and I don't use any custom style rule files, to my knowledge.

Terry, Thanks for letting me know that folks are trying to fix the screenshot upload problem.

And from the articles you link me to, it looks like my problem is pretty advanced. None of the usual suspects are actually guilty here.

Well, after using Firefox all my web-browsing life, I had to dump it and use Chrome from now on.

Too bad this problem could not be fixed.

I'm back with FireFox 'cause the problem is gone.

The problem may have vanished on its own, or because of my attempt to fix it. I don't know which. But here's what I did to try fixing it:

I re-installed a large number of my fonts from a system backup that pre-dates the problem. That is, I just drag-and-dropped the font files into the Windows 10 fonts folder/widget, and opted to "replace" or "over-write" the fonts. Windows 10 did not recognize many of my fonts as valid font files, do I had to skip them. But for every font file that it did recognize and flag as "already existing", I opted to "replace".

After this, I re-installed FireFox and the problem was gone.

Here's why I suspected that restoring my fonts from a backup might fix the problem:

I read another forum post about someone who had a similar problem, in which they fixed it by doing a font folder over-write with a new download of Windows default fonts.

I had recently added a lot of fonts to my font collection. And when I did so, I opted to replace the existing fonts. Hence, I could have accidentally replaced some fonts that worked, with some by the same name that did not work under certain conditions.

These clues prompted me to try restoring the fonts from my backup.

Again, I don't really know why the problem vanished, whether it was my doing or just some other accidental self-fixing.

That was a good instinct. Usually in the case of a replaced font there are weird letters; it definitely was not obvious that missing letters could be caused by a bad font. Worth keeping in mind for future threads.