I think with the aid of Evesham's Tech Support line I have solved the problem. They reckoned that all my PC woes were caused by the build up of Static Electrickery on the hardware in the case. They suggested that I unbpugged the PC and hold in the 'go' button for more than 20 seconds. This was to bleed the static which was obviously interfering with everything.
Did what they said and it now works.
Weird.
DeepC