what i want to know is how the heck did this get set in the first place. Someone @ HP needs to check their image file that they install from.
Try and boot into Safe Mode 1st and logon using the Administrator account. The password should be whatever he set it to, or blank because HP wouldnt be stupid enough to lock people out of the admin account on their computers. If they did then do what i described below.
The best thing to do is try to use a password reset disk for the admin. If that doesnt work then, if you have a Windows 2000 CD, then boot into the Recovery Console and reset the password from there. There is a bug in XP that should let you use the Win2k recovery console in XP, even though your not supposed to be able to.
Did this always happen or just now?? Also was the computer ever connected to a docking station or is this a new account. XP Home should log the root account on automatically once you create it. Someone mustve set the security policy not allowing his account or group to be able to be logged on. By default there is no way it shouldnt let you logon.