Spot -

Sounds a little like a problem I last encountered with Win98. Turns out a few bits in one RAM stick had gone south. I haven't heard of the problem with XP, but it might be worth a quick check.

Most of the older RAM-check utilities (the ones I have) won't load, even in DOS, on an XP loaded machine; but you probably have more than one chip installed so you could just pull one (it will likely leave enough for the system to limp, at least) and see if the problem goes away. If not, put that one back and pull another one. Just remember all the warnings about grounding and ESD while you're at it.

If the error gives a consistent ref to a specific memory address, you might be able to home in a little quicker, but physical memory maps for a specific machine are a little hard to come by.

Other than that thought, about all I can offer immediately is sympathy.

John