I've recently built a new computer and based it on a MSI KT3 Ultra2-R motherboard. In the beginning it booted just nicely and I was able to install Win2k and all other programs I wanted. Then I shut the computer down for the night and the next day it started making trouble. When I turned the computer on it booted and began to start Windows but then suddenly rebooted, sometimes it managed to start Windows but then suddenly rebooted after a couple of minutes without any warning. This motherboard comes with hardware monitor for temp. and voltage and the program supplied with the motherboard gave no warning on abnormal values.

In an attempt to find out what was wrong I started to take expansion cards out one at a time. I even went as far as doing a complete memory test with a program called Mem-test which is OS independent. This test ran to completion twice both taking approx. 25 minutes seperated by me rebooting the machine.

My question is then if anybody here has any idea what the problem might be? Everything I've done to locate the problem indicates a motherboard problem, but as the problem only seems to occur when starting Win2k, I'm confused.

I should probably add some specs:
CPU: Athlon XP 1800+
Motherboard: MSI KT3 Ultra2-R
RAM: 2x 256 MB PC2700 from Samsung
Cabinet: Cheiftec AX-01SL-D (Aluminium cabinet with room for 4 additional fans only one running cooling HDDs)
Graphics: ASUS V8440 (GeForce4 Ti 4400)
Sound: Sound Blaster Live 1024
NIC: Level One FNC-0109
HDDs: IBM 120GXP 80GB and IBM 75GXP 30GB
DVD: LiteOn 16x
FDD: standard FDD

I've been reading over at AMDMB that The MSI KT3 series has had problems with certain memory. That Samsung is probably pretty good, but if the mobo doesn't like it for whatever reason, you're SOL.

I'd try obtaining another stick of RAM and see if the stuff continues. The only other thing that comes to mind is an improperly mounted heatsink or not getting enough power.