Ah, windows ... nothing is really secure in it. :no:
Start up regedit
H_KEY_LOCAL_MACHINE > Software > Microsoft > Windows > Current Version > Policies
click on the Ratings folder.
In the right pane of the RegEdit window, you'll see an icon called "Key". -- Delete it.
Close up regedit ... your done, the password for the content adviser has just been deleted. You'll still have to go into Tools > Internet Options > Content > And click the disable button.

But instead of asking for your current password, its has no clue so what it is either anymore so it will ask you for a new one, once you put it in, content adviser will be disabled and your new password set.