I think those may be text labels for missing icons. Possibly an icon font is loading from a blocked source. Could you test:

Firefox's Tracking Protection feature and extensions that counter ads and tracking may break websites that weren't built to operate normally without the blocked components.

Do you notice the shield icon toward the left end of the address bar, near the lock icon? Tracking Protection is blocking something -- click that shield to turn the feature on and off for that page. More info on managing the Tracking Protection feature in this article: What happened to Tracking Protection?.

Also, extensions such as Adblock Plus, Blur, Disconnect, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix should provide toolbar buttons to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you may need to click the button to see what's going on and test whether you need to make an exception for this site.

Thanks for your reply, jscher. Yes, it shows that tracking protection is on. But I don't think that's the issue ----- I went back to the page which was displaying the interference and there was no interference this time. (tracking protection still on). Also, I don't have adblock or any other addons of that nature. If it was due tracking protection I would expect it to show up consistently on the same page, but it does not.

Maybe the problem is only with a particular video player (judging from the labels in your screenshot) that isn't used on every page. Or ???

Intermittent issues are very challenging to solve...

I don't think it has anything to do with the video player for that particular page either ------ as I mentioned, I went back to the exact same page that exhibited the problem. I can't imagine that the video player was changed in the meantime. I encounter this problem intermittently ONLY with Firefox and ONLY with dailymail.co.uk. Articles that exhibit this problem in Firefox are fine in Chrome or Edge. Thanks again.

Next time, could you reload bypassing the cache. Either:

• Ctrl+F5
• Ctrl+Shift+r

This may be a stupid quesiton, but by "reload bypassing the cache" do you mean doing Ctrl+F5 before reloading?

Well .... I didn't realize the Ctrl+F5 did the reloading. ....... Anyway, the problem reappeared on another dailymail.co.uk article and I pressed Ctrl+F5 --- and the problem disappeared. Wonder why it occurred in the first place?

Hi, there is possibly a java script or the page is full of telemetry which is what the site gathers for statistics, and google ad sense and a wack of things. If someone leaves a comma out of place in the code all goes weird.

You can see what the code looks like by Right Clicking and View Page Source to give you a idea what Firefox has to look at to give you what you see.

If you know a trouble area you can Right Click and Inspect Element to see if it is the Video Player.

If you are all fixed up great, please select the answer that was the solution

Well, it seems there is a correlation between a video and the interfering text I had mentioned. On pages where the interfering text appears, there is also a video which displays only the top quarter inch of the video. Inspect Element tells me nothing --- I am not skilled enough to interpret the cause of the problem. One thing, though ---- a simple "refresh" (either by F5 or clicking the "refresh arrow") solves the problem. Which leads me to ask: why didn't Firefox read the page code correctly in the first place? If the page code had, as you suggested, something on the order of a misplaced comma, then wouldn't that misplaced comma also show up in the refreshed version and cause the same problem? To me it seems that something is wrong with the way Firefox deals with the code.

This is the problem with intermittent issues: you have to investigate it at the moment it happens.

You could keep Firefox Browser console open (minimized to the Taskbar) and look for recent error message when you notice the layout problem. That may or may not actually tell you what happened.

You can open the separate Browser Console window using either:

• "3-bar" menu button > Web Developer > Browser Console
• (menu bar) Tools > Web Developer > Browser Console
• (Windows) Ctrl+Shift+j

More info on the Browser Console: https://developer.mozilla.org/docs/Tools/Browser_Console