Just to conclude,
I could not identify what was wrong and ended up getting a new
motherboard and everything is back to normal (after a lot of
re-installing).
Yesterday whilst I had all the bits and pieces all aver the desk, my
13yr old son commented on hearing a "pop" from the back of the CPU on
the evening prior to my PC's demise. Although it must have certainly
run on for the remainder of the evening, I now conclude that something
on the MB must have blown.
Thanks for your help


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Pommie5