Many thank for the replies from both James Harper and Rohan McLeod. The actual failure is rare and very likley is temperature related, failing at low temperatures say below 20 to 25 degrees, it failed this morning for the first time in quite a while, this being the first cold day in a LONG time. The system shows no problems at all once it is running. All tests on the hardisk, including thoses suggested by James being OK. The system will compile a kernel OK and from past experience this is one of the best memory tests on the planet. From recent behaviour I think the most likely cause is the spindle motor on the drive is slow in starting. I will though check __ALL__ connections as I have had some __VERY__ strange things caused by both SATA data and power connectors not being fully home. BTW, the power supply tested OK, sudden changes in load effecting the voltages not at all, allthough the CPU voltage was varing around 10 mV, not worth worrying about though. I am going to rebuild this system shortly (like next week, when my new case FINALLY arrives) may just leave it switched on for now, its very unlikely a thunderstorm will occur for awhile now. The power cost cetainly will not break me. Lindsay PS, had around 75 mm of rain last night, man that was good to hear after almost 5 months of nothing, nice cool day to so can get some work done. Theres a fair number of people around NE Vic that will be glad to see the back of this summer!!!!