Help - system turning itself off?

[Rythmic]

Could be a short somewhere - seen that on a friends system before (I thought at first the problem was the CD-ROM drive, cause it would happen when the CD spun up - the vibration was actually causing a dangling molex to hit the motherboard...)

[Alistair]

talked to our electricians & instrumentation people @ work & they thought it could be a dry joint in either the Motherboard or PSU. It was suggested that I very lightly tap the PSU or Motherboard with the plastic end of a screwdriver to see if this would replicate the behaviour - it didn't. It ran prime 95 on the most exhaustive test for 7hrs till lunchtime today no probs & have it now running memtest.

I did have another thought - I think I was using a newsreader software on each occasion this has happened & I'm using winxp sp2 with its built in firewall. Just wondering if the new sp2 firewall wasn't up to the task, would an attack be able to shutdown the PC ?