401 forwarding

Hi, I’ve installed WordPress on a site and need a separate (non WordPress) webpage in a subdirectory of the same installation. This works when accessed by going to “http://site.com/privatearea/index.php”. However, as soon as I password protect this directory via htaccess, WordPress forwards me to a “nothing here” webpage. It seems to detect a 401 (?), but “takes care” instead of letting the webserver ask for login. What am I missing here? How can I fix this? Any hint is appreciated.