Welcome to the wonderful world of Windows bugs. Lately, there's been a universal exploit for XP and 2000 for the RPC bug that works independently of Service Pack level and similar factors. And this opens the door wide for script kiddies in Windows - if you're running your Windows system without a hotfix, you'll soon become an involuntary employee of some script kiddies ...
At INSTANT NIRVANA you can find the original article.