Javascript Error in a basic include

[Kaelon]

Here's the code of a simple page I'm using just to generate a uniform "look and feel" for some custom content:

<?php

define('NO_REGISTER_GLOBALS', 1);
define('THIS_SCRIPT', 'main');

chdir('/full/url/to/my/forumsdir');

require_once('./global.php');

eval('print_output("' . fetch_template('mainpage') . '");');

exit;
?>

... where "mainpage" is a simple template that calls $header and $footer.

Why do I receive Javascript errors? This is in vB3.5 Beta 3.