well how about the script tags you have with no source attribute?
<script type="text/javascript"></script>
Also all of these are incorrect syntax
<script src="/js/jquery.js" type="text/javascript" /></script>
<script src="/js/imperative.js" type="text/javascript" /></script>
<script src="/js/jquery.cycle.js" type="text/javascript" /></script>
<script src="/js/jquery.lightbox-0.5.js" type="text/javascript"></script>
<script src="./js/validate_plugin.js" type="text/javascript" /></script>
That slash should only be present in XHTML at the end of empty tags, not Script tags.