Navigate to \desktopmodules\smith.buynow and edit the productdetail.ascx try commenting out or deleting the following lines at the very top:
<link href="/css/lightbox.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="/js/prototype.js"></script>
<script type="text/javascript" src="/js/scriptaculous.js?load=effects,builder"></script>
<script type="text/javascript" src="/js/lightbox.js"></script>