Thanks for that.
Now it has Gerry, but not before something happened. - When I now press the
Screenlock and the far right diode lights, scrolling is back to normal.
As as the diode goes out, I have the original problem again!
I should mention that I've been having trouble with a new Logitech USB
Optical Mouse that refuses to work with a USB SP/2 Adapter but works fine
plugged into a vacant USB port on the front of the PC. I think I may have
accidently clicked YES to something - not sure what though. - Andy