As well as the other suggestion, it could also be caused by spyware or
possibly even a virus. Run an up to date virus scan on your PC (you DO have
AV software don't you?) and check for spyware using AdAware and Spybot (both
easily finable with a quick google search).
Both AV and antispyware have always been in place. I've always used a
firewall too.
I think the problem is that XP tries to do too much, and too much
automatically. It's just top heavy and it's in the process of collapsing.
I'm betting a big part of the problem is that the registry is horribly
cluttered with all sorts of outdated and useless information --I'm finding
references to video and music files I created and/or watched more than a
year ago that have long since been deleted from the system, as well as every
program I've ever installed--no matter that they were supposed to have been
uninstalled. There's a network adaptor in there too, it never worked with
XP, but it refuses to go away.
But I'm too afraid to monkey with the registry, and I'm wondering why
there's no Freeware tool to address this problem.
Right now, I've placed XP in a rack, and when I really need a lightweight
OS, I take it out and put in a specially stripped down version of 98...