Delete the following registry key:
(or rename it, if you don't like deleting registry keys)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Ratings\Key
You should then be able to open Internet Explorer, go to Tools | Internet Options | Content, and click on Disable. When asked for a password, don't enter anything (the password is now blank), just click OK. This will disable the password.
You can then re-enable it and reset the password.
This should take care of it. If you're not sure on how to edit the registry, find someone who is and have them do it.
Jason H.