Well, Simon and BHSChild, I was of the same opinion, so today I bought and installed a new DDR RAM strip, 1gig. It has made not one scrap of difference, the machine performs just the same as before. Another possibility disproved.
I've also removed some programs that I was not using, some more video, and downloaded and run Malwarebytes scanner, a full scan exposing no malware whatsoever. I've reinstalled Outlook Express from the Win CD (a trap for young players in there, it removes all the optional items, and you have to elect to reinstall them) and checked every program I have to see how they load. I find:
Spybot jams ('Not responding.')This was downloaded/installed well after the trouble started, in response to the problem.
MS Outlook jams. It is only there to supply files needed to run my old MS Office under XP.
Outlook Express loads verrry slowly and not consistently, from 30secs to 90secs. It is my email program, but I could remove it and use Opera's mailer, but that would leave whatever the problem is lurking in there somewhere.
I also have to be very deliberate with the mouse buttons, working fast is apt to cause 'Not Responding' problems.
I have one more thing to try, a program that Mick suggested, but it is 10.15pm and I'm sick of today. Goodnight.   Chris.