I bet that's the same kind of error that macgeek caught earlier. Change that line to
<?php
if (!isset($product_data->unique_hash)){
?>and that should take care of it. There's a few more lines that will do the same thing because of the isset(), so either change your copy or get the updated one in the post above.
Boo on Dreamweaver. We use jEdit, and I haven't found another text editor I like better.