I'm inclined to agree with Charlie's diagnosis... weak PSU.
What are the +3.3v, +5.0v, and +12.0v 'A' or 'Amp' ratings, from the sticker on the side of your PSU?
The VIA KT133 chipset can not run at 133 MHz, and all XP type processors run at 133 MHz, or faster.
The VIA KT133A chipset IS capable of 133/133
Maybe that's what VIATech's website was refering to?
When you first try to install WinXP you have the option of running a 'compatibility check'.
Did you run it?
Here is my new PCChips M848A' ">http://img.photobucket.com/alb...2_T-2-3-3-6-2_M848.jpg v2.1, with a 1700+ @ 2411 MHz, and my trusty old PCChips M810L' ">http://members.lycos.co.uk/mmm...00MHz_Sandra_tests.jpg v7.1A, with a Barton 2500+ @ over 3500+. Some of my fancy cars are on this pag