Thanks for your replies, folks!
No one solution on its own worked, but a combination of Avast, AVG and Stinger seemed to do the trick.
Spanner, that fix you found looks rather hard for a computer
dumpkopf like me! And the F-Secure scanner only works in MS Internet Explorer - I run Firefox. But between you guys you came up with the answer and I'm very chuffed
.
Thanks again,
Kev.