You may have encountered same “entertaining” caching behaviour of the browser that I just did.
It’s 5:18AM here. I just spent four hours trying to get similar setup going, just to find out that I’ve been getting the initial application/x-httpd-php file from disk cache instead of server itself. It got cached when I first tried to load the page, and there indeed was a configuration problem. After that every subsequent refresh just gave the php file from disk cache and asked if I’d like to save it. In total frustration I tried http://host/file.php instead of just http://host/ – and of course it worked. Five hours of solving a problem that was not.