(Many companies put their name on Logitech mice, so there is a possibility that your mouse is just co-branded by Evesham.)
Spot on. Logitech M-S48a.
I'm going to take it apart tomorrow and clean the contacts as well. I did a system restore from a point a month or so back and it worked fine for about half an hour. I scrolled through things properly. It then started to display the same problem.
DeepC