Thanks Boggin. I will try to get a screenprint in due course, but I think it is blank apart from the heading. The only problem with disabling services as you suggest is that it is very intermittent. It may happen only once or twice a day, I think, so it would be difficult to draw any conclusion from whether it seems to be happening after disabling the services, at least until it happens, which may take ages. And since there is no trace of its happening after the box has closed, so far as I am aware, I would have to sit in front of the computer all day, with most of the functionality turned off, to watch for it.