Problem with Calendar after upgrade to 3.7.2

[BTTF.com]

Here's the offending plugin, which is what I suspected, but I don't know why going from 3.5 to 3.7 has made this no longer work. Someone at vBulletin gave me this code 3? years ago to put into my global_start hook.

ob_start();
require("/home/bttf.com/public_html/header.php");
$head = ob_get_contents();
ob_end_clean();

ob_start();
require("/home/bttf.com/public_html/footer.php");
$foot = ob_get_contents();
ob_end_clean();

When I disabled this hook, the problem went away. How do I fix it?