Is it still that way if you disable all extensions, CTRL+F5 the page, and so on? Or use a different browser such as Chrome?
I've tried all that except for using a different browser.
Have you tried running an operating system released in the last 12 years? I've no idea whether that makes a difference or not, I'm not sure whether it impacts on Firefox at all.
Probably doesn't, and yes, I run xUbuntu on two other computers, but they're not networked. The problem only arises in Windows XP, which many other people still use (and which, while I realise that it's getting a bit long in the tooth, works perfectly well still for my limited purposes).
One is a freecycled laptop courtesy of TW on which I write minutes of meetings, which doesn't need to be networked, and one is the computer on which I write, which is not networked to avoid distraction. Non-networked is good sometimes.
I've tried all that except for using a different browser.
Probably doesn't, and yes, I run xUbuntu on two other computers, but they're not networked. The problem only arises in Windows XP, which many other people still use (and which, while I realise that it's getting a bit long in the tooth, works perfectly well still for my limited purposes).