How do,

Getting in a bit of a twist here so would welcome some help if anyone understands the problem I'm having.

I've got a web server running IIS 7 hosting several PHP sites (with the CURL extension enabled). Several of my sites (such as Wordpress) use CURL, but my proxy (locekd down as it's at a school) is refusing it access. I've added a rule to allow unauthenticated access out for my servers, which now let's CURL run but with a 404. On checking the errors, somewhere the URL of the CURL request is being changed to an IP (for instance, Popular Science - New Technology, Science News, The Future Now is becoming - which is the host - so fails with the 404). Yet, if I create a PHP page that forces CURL to use the proxy, it let's it out and retrieves the correct feed using the URL, not the IP.

Does this make any sense and if so, any pointers would be really welcome.