From:
http://www.kellys-korner-xp.com/xp_abc.htm
Content Advisor
Remove the Content Advisor and Ratings Password
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Ratings
Open your registry, find the key below. Single click on the key to
highlight it, press the DELETE key, or alternatively select Delete from
the Edit menu. Close Internet Explorer, re-open it, and the Content
Advisor feature should be disabled.
or
http://www.winguides.com/registry/display.php/60/
All the Content Advisor settings are stored in the key below. If you no
longer have the password, then simply delete the key, and all the
settings will be removed.
Open your registry and find the key below. Single click on the key to
highlight it, press the DELETE key, or alternatively select Delete from
the Edit menu.
Close Internet Explorer, re-open it, and the Content Advisor feature
should now be disabled.
Registry Settings
User Key:
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\
Ratings]
System Key:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\
Ratings]