Yes, it did help, Duncan.
Bertha, you are a genius.
I have no idea what IE9 is, but I got onto that link and the problem described there was exactly what was wrong with my computer. I followed (very gingerly) the steps indicated there. I balked a bit at 'delete personal settings' for fear of what I may lose, but I bravely went on and bingo, the problem has disappeared.
I had to use a password to get back into LGC but fortunately I hit the right password second try. My homepage (Google) had disappeared, but I have got that back again now. So all is good.
Bertha, you should open an on-line consultancy service!