You more that likely have XP set to automatically reboot when it BSODs. To disable this, go to control panel > system > Advanced > Startup and recovery > uncheck automatically restart, set your Write Debugging Information to Small Memory Dump or None, your choice.
Send back the BSOD message so we can troubleshoot it. It may also be in your Event Log in the Administrative Tools.
I gave wrong info, system doest reboot but freezes up.
iwill vd133 pro
512mb pc133 oem,
3dlabs oxygen vx1
via 4in1437 drivers from viaarena.
MACHINE FREEZES UP ONLY WITH XP, W2K WAS RUNNING FINE.
HERE IS THE EVENT LOG
Event Type: Error
Event Source: ACPI
Event Category: None
Event ID: 4
Time: 4:05:33 PM
AMLI: ACPI BIOS is attempting to read from an illegal IO port address (0xcfc), which lies in the 0xcf8 - 0xcff protected address range. This could lead to system instability.
I had that problem under XP for a while, I discovered it was a clash of drivers between my iWill card drivers, and the Sound Blaster Platinum software (not the drivers). When I uninstalled the software, leaving just the SB Plat. drivers, the problem went away. Try using the 4 in 1 from the VIA site, and generally update all the other drivers.
Sorry to sound a little vague, but good luck anyway.