I thought I'd better close this out.
There is a solution - I called in a computer expert (shame) who prescribed the following:
upgrade to Windows 2000.
And it worked!
Why do IT people always do this - if there's a nasty problem they simply bypass it with an operating system upgrade?
The technical reason why it worked,apparently, is that Windows 98SE is a "dog" and not able to find a suitable driver if it bit it in it's hard drive.
Whereas Windows 2000 is less so.
So now you know.