Heratech

http://www.thesitewizard.com/apache/access-non-drupal-folders.shtml

I was trying to password protect a subfolder of this website (nevermind which one). The problem was it kept giving the Drupal 404 error (The page you requested was not found.). The solution is to specify a 401 ErrorDocument line:

ErrorDocument 401 401.html

and create that file (touch 401.html).

That fixed it.