I'm sorry ... there's just not information in the post to ascertain the source of the problem.
Please list your complete system specifications, and a detailed observation of what the computer was doing before the lockups began (something a little more specific than "It was acting a bit weird", please.)
Problems like this typically occur because of 1.) a bad memory module, 2.) an older ACPI-BIOS that is incompatible with WinXP (which may require a flash), and/or to reinstall the OS with a Standard HAL and APM Power Management (sometimes with the APIC Interrupt Controller disabled, as well), 3.) or an incompatible/out-dated driver for a device, such as your modem, NIC card, or sound card.
Which one of these might apply in your situation (if any) ... that's for you to discover, at this point.
Here's a memory testing program. I can provide this for you, if nothing else:
<A HREF="http://www.memtest86.com/" target="_new">Memtest86</A>
Toejam31
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