[Idiot Mistake] Need Help

Ok, So I am using a $_GET function as a main navigation tool. Yes, I am using PHP, I did not come here to get ridiculed, I came here for assistance.

So I have the script something like:

<?php
$page = $_GET['p'];

if ($page == ""){
require 'index.htm';
};

if ($page == "about"){
require 'aboutme.htm';
};

if ($page == "links"){
require 'links.htm';
};
?>

And I have seen this work before, However I am running this off a different server on my own IP address instead of on a host. Basically the error I keep getting is that "p" is not defined. So, simply "page.php" will not load, however "page.php?p" will load. I have never had this happen before. Usually if the $_GET is set to '', then running page.php by itself will just cause the index page to show up instead.

I really don't understand what I did wrong. Please help /prog/.

THE MOST EFFICIENT WAY TO DO THIS IS TO USE STATIC FILES, NO INCLUDES.

USE SHELL SCRIPTS TO GENERATE THEM IF YOU WANT TO USE SEPARATE HEADERS AND FOOTERS
OR YOU COULD EVEN USE PHP FROM SHELL SCRIPTS IF YOU LIKE.