Is this on your local testing machine that you administer? This looks like an IIS error of some type that is coming from the server, it does not appear to be a php error. Are you able to view any php pages on your server? If this is a hosted environment you will need to speak to your host to enable error reporting in IIS. With a generic 500 level error it just means that something happened when processing the php file, no specific error is being reported.