Ok, my clock is acting up again, so I did a little research. Here's just one of Many reports that I've found - and still no real resolution.
FYI To Microsoft: Windows Time Synchronization Completely Broken (Vista, 2003, XP are all broken) - TechNet Forums
If I try to get a fix from Microsoft I get an error: your system is already updated. Argh! Finally I found an update page that tells me I have to uninstall XP SP3 before getting the update!!  I saw a place to turn off the synchronization but I'll have to find it again. After that I'll just do it by hand. Thank you very much, Microsoft! (not!)
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