windows xp “hidden” users

Need some help with this: I’m working on XP Home and I discovered I have a “hidden” user created in my system. That is, there’s a directory structure and files for this user, I can access it from the classic logon screen (logon window), but it doesn’t show up on either the XP logon screen or the user’s management window (from Control Panel).

Any ideas on how that user ended up in my system? And how to convert it to “regular” user?