Hello again,
After reading my initial post, I was shocked (ahem) to notice that I
said 'I have bypassed the psu earth.........' Let me elaborate on
that. What I meant was that the pc was connected to the mains in the
totally normal way. All I did was attach an additional cable to the
earth contact of the extension lead socket to the internal pc case
chassis. I know that I could still be dead of course.
andy