More Auto Rebooting

Remember when I posted about my main pc rebooting? Well it’s still happening. It also happened today (consistently) when I took it round PCJunky’s house. This ruled out the usb devices, mouse, keyboard, psu cable (incidentally I had to replace the PSU as it didn’t survive being switched off whilst we were on holiday strangely enough), monitor and sound cables. The system will now consistently reboot (as if I had pressed the reset button) in one of three random places. Either immediately the first w2k loading screen finishes – where the bars go across the screen normally the screen will then clear and the windows backdrop appears, after the pc has (automatically) logged on or when everything in the startup group has finished loading and about 10 seconds of doing nothing. 3 places for it to reboot and then the machine will behave for a while……
We did find out that if the machine is booted without the network card plugged in, on the second and subsequent boot the machine runs stable. Also if I boot to an alternative OS/CD then the system is also stable. I’m going to use the msconfig tool later tonight/this weekend to see if a clean build has the same symptoms.
What is annoying is that there are no bsod or log files generated so I’ve nothing to debug and of course all these reboots dont do the data on the disk much good!