Neil introduced me to MaxBlast - a useful piece of software that allows you to do all sorts of things to a hard disk. Initially, I just used it to reformat the e drive because it sometimes wasn't showing up in explorer. I discovered that MaxBlast can also be used to clone a hard disk, so that gave me the idea of buying a new drive, cloning the existing c drive to it and hopefully, that would help things.
A quick trip over to Novatech's web-site and within minutes I'd located a 250Gb disk for under 35 quid to replace the ageing 12Gb one currently limping along in the PC.
The new disk turned up today. It took MaxBlast around 25 minutes to clone the disk and after a bit of confusion on my part about the boot sequence (Neil put me straight!), we were up-and-running.
A most rewarding day!