Thanks for help so far!
I don't think it's just the graphics card as, I forgot to mention in the original question, there are no "beeps" to be heared either when the comp is first switched on.
I could try the CMOS battery, but cannot do anything with the graphics card as it is integrated into the motherboard.
?new motherboard? ?new chip?
Cheers.
Mike C.
It was on the basis of the lack of POST beeps that I based my diagnosis of failed processor, which I still think is the most likely cause. A failed CMOS battery would not prevent the machine from booting, it would go straight into CMOS setup
"Are we likely to be talking motherboard, Pentium chip, or both, here? "
Unfortunately, if it is either, it's difficult to tell without having the machine in the workshop.
I can think of one other potential cause of the symptoms you descibe, but it will only apply if you've had the machine apart for any reason - failure to reconnect the additional (Yellow and Black) PSU-Motherboard cables!
That's cool Roj:
I had not had the machine apart at all. It just suddenly stopped working!!
I am currently awaiting some feedback from the tech support people @ Packard Bell as I don't feel too confident about just buying a new motherboard etc without being 100% sure.