I haven't experienced that myself, however my XP installations are all in Virtual Machines, but that shouldn't make a difference. I haven't come across this in the forums either so perhaps your best bet is to contact Technical Support directly. It's free and the link is in under Useful Links at the top of the forum.
Edit: make sure your system is totally up to date with all updates even those for parts you may not use (IE for instance which should be IE8 for XP) and then run the MVT http://mvt.mcafee.com/ see if that helps.
Many thanks for your rapid response; I'll follow up your suggestions.