Found this inadvertently yesterday, (and also stumbled on your post on the Cow – the same day!), and think it may apply to your problem. I believe the problem is with Windows XP Service Pack 2, and this link contains a download which might fix the problem (not on SP2 yet, so I can’t personally confirm). Hope this helps.
https://support.microsoft.com/?kbid=886716&SD=tech
Cheers, Keith