I've got a URL for any Expensive file.

http://www.example.com/aff/banners/banner.swf?tag=http%3A%2F%2Fwww.example.com

It features a GET param, that contain a encoded URL. After I take away the . in .com from the encoded URL within the GET param, the Expensive is came back fine.

However, after i include that period, it 403 Forbidden on me. Changing the time with %2E does exactly the same factor.

I've examined the 2 .htaccess files during my directory, but both of them are doing URL spinning only and do not have anything related to the Expensive file/directory under consideration.

I've also checked out the Apache logs.

How do i evaluate which preference/configuration/etc is causeing this to be request forbidden?