First off, maybe off the topic, I would find more ram for your system. Running win2000 on 96mb, is pretty darn low, real low on resources.
Your problem maybe heat or power realted. These are areas to look at and proceed from there. Remove case cover and inspect for dust which retains heat on componets, blow it out. Then verify *all* are running and clean them as well for best operation. if your system is slightly noisy, it could an intermit fan operation, thus inspect well. A failed fan at the power supply will eventaully cause the whole p/s unit to fail as well, so replace. There's no repair here just replace and with a higher wattage one at that. To help determine a heat problem, usualy best to blow a home fan inside to cool it further and if problem seems to settle down that maybe it, too hot. Over time, componets do degrade and reboots or shutdowns are a result.
good luck -----Willy
Sometimes the computer shuts down(though its rare)it happens very fast,but what I am able to read is "beginning physical memory dump" .After this it reboots. OS 2K pro In case the amount of memory is needed,this is what it says in system properties-97,824KB RAM