Guys,
First off, thanks for all your suggestions yesterday.
I printed them all off and set off for home to spend a couple of hours cursing at my PC.
When I powered up the PC, pressed 'Del' for setup and checked the boot options in the BIOS I could see there were 3 options for boot device as opposed to the 2 that had been there over the weekend. When I went into the 3rd option to change it from 'Disabled' I now had 3 boot devices to choose from. I selected the 'new' 3rd one and booted up the PC.
Everything came up fine! Windows initialised; hard drive available; all data accessible.
It would appear that the only 2 options I had to boot up previously were:
1. DVD drive.
2. Generic Storage Device
I now had a 3rd option which is apparently the hard drive.
Obviously I'm delighted that my PC and Hard Drive are working again but I'd like to know why (for the 2nd time is as many years) this problem has occurred.
Is there anything I should check while I have the machine working again?
Thanks again for all your help on this so far,
Paul