Could you run the same browser (and version) on your laptop as you do on your desktop? If you can, does this solve the problem?
Yes, I run Chrome on all my devices and it's only the lappy that does it.
(I think) 150% scaling somewhere.
Tried that. It was set to 100%, but I have swapped that around to no avail.
Just tried Edge, and it's OK. Weird.
Not even within the browser?
No. Just tried altering the zoom in Chrome and it makes no difference. Also, I can zoom around on my desktop and Surface Pro and its solid OK. It's OK on my Android tablet as well.
I found Options/Content/Fonts and Colours was set to Times New Roman 20, whereas the other machines were set to Times New Roman 16.
Ah Ha. That was the problem. (been running down the investigations and unfortunately left yours to last

).
I had the text size in Chrome set to 'Large'. Changed it to 'Normal'. Problem solved.
Thanks to all for your inputs.
Now then, what about my other problem with file renaming
HERE?