Hi, Chuck.
As ever, I appreciate your advice.
In the end, I got the hump ... (yes, it's true, I had a mardy) ...
... and I uninstalled Firefox, and downloaded it from scratch.
It now seems back to normal.
Here, by the way, is the stupid YouTube video which I saw and, stupidly, followed. I don't need to tell you not to try this, because, unlike me, you are not a technical retard.
https://www.youtube.com/watch?v=gP7WC6G8Igs&fea ture=PlayList&p=6E54E6A0C10A7B0E&playnext=1&pl aynext_from=PL&index=43
Oh, and here a clip showing why only half-wits like me would be duped by goglogo.
https://www.youtube.com/watch?v=iS_BFLvWMwY
Love as ever,
Seagull
x