I saw some little thing in your code. Your content is being included basis a parameter supplied from the $_GET method. Look almost at the end of the page saying like this
[php]
<?
if (!$c) { $c="main"; }
$c = "$c" . ".inc.php";
include("$c");
?>
[/php]
In php 5 you should specify that it is a php script, otherwise the parser will discard it.
Try this code and advise with the results.
[php]
<?php
if (!$c) { $c="main"; }
$c = "$c" . ".inc.php";
include("$c");
?>
[/php]
If you have an error in your code, the parser normally should show you the error.
Once you have tried this one, advise if it solved the problem.