I had been working on the computer for a while and then left it for a couple of hours. When I sat down to work at it again, the monitor went of like a gunshot as I touched the mouse!
To cut a long story short, NEC (Part-Serve) in South Africa have repaired it under warranty - in spite of the fact that I bought it from B&H in New York. They replaced/repaired the power supply and serviced it while they were about it.
Well done NEC!