response headers buggy

I have a problem with response headers since version 2.0. Since i want post versioning, i decided to wipe my installation and start from scratch with a clean, brand new 2.6 install – but the problem is still there! The only differences from a standard install is the blog home is the root, WP is in it’s directory, and i use permalinks.

When i access my homepage or any existing page, say, the about page, the headers look fine:

Date: Wed, 23 Jul 2008 03:52:34 GMT
Server: Apache/2.0.54
X-Powered-By: PHP/4.4.8
X-Pingback: http://fitoterapia.pro.br/wordpress/xmlrpc.php
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 1876
Keep-Alive: timeout=5, max=99
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8

200 OK

But when i access a non-existing page, like this one the response headers look wrong (see the last line, shouldn’t the text say Not Found?):

Date: Wed, 23 Jul 2008 03:54:58 GMT
Server: Apache/2.0.54
X-Powered-By: PHP/4.4.8
X-Pingback: http://fitoterapia.pro.br/wordpress/xmlrpc.php
Expires: Wed, 11 Jan 1984 05:00:00 GMT
Cache-Control: no-cache, must-revalidate, max-age=0
Pragma: no-cache
Last-Modified: Wed, 23 Jul 2008 03:54:58 GMT
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 1382
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8

404 OK

How come it says “404 OK”?

The installation is fresh, no plugins, the server is Media Temple. I use the permalinks structure /%category%/%postname%/, and htaccess is just the one WP provides for that:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

This problem also causes existing pages not generated by WP to have a 404 response header (say if i put a html file somewhere in my direcotry structure and link to it).

All help will be much appreciated.