I just took a look and see you are using HTML5. So after first glance I am thinking your HTML5shiv is somehow the culprit too as that is your workaround to get HTML5 elements working in IE8 and below. Are you using the latest version of that JavaScript that you should be using? The one I use with no problems for my HTML5 sites is this one:
Maybe try that one and see if it fixes your problem. If you want a compressed version of one I will copy and paste it here, this one works for me but could be outdated from the source above:
(function(a,b){var c=function(a){return a.innerHTML="<x-element></x-element>",a.childNodes.length===1}(b.createElement("a")),d=function(a,b,c){return b.appendChild(a),(c=(c?c(a):a.currentStyle).display)&&b.removeChild(a)&&c==="block"}(b.createElement("nav"),b.documentElement,a.getComputedStyle),e={elements:"abbr article aside audio bdi canvas data datalist details figcaption figure footer header hgroup mark meter nav output progress section summary time video".split(" "),shivDocument:function(a){a=a||b;if(a.documentShived)return;a.documentShived=!0;var f=a.createElement,g=a.createDocumentFragment,h=a.getElementsByTagName("head")[0],i=function(a){f(a)};c||(e.elements.join(" ").replace(/\w+/g,i),a.createElement=function(a){var b=f(a);return b.canHaveChildren&&e.shivDocument(b.document),b},a.createDocumentFragment=function(){return e.shivDocument(g())});if(!d&&h){var j=f("div");j.innerHTML=["x<style>","article,aside,details,figcaption,figure,footer,header,hgroup,nav,section{display:block}","audio{display:none}","canvas,video{display:inline-block;*display:inline;*zoom:1}","[hidden]{display:none}audio[controls]{display:inline-block;*display:inline;*zoom:1}","mark{background:#FF0;color:#000}","</style>"].join(""),h.insertBefore(j.lastChild,h.firstChild)}return a}};e.shivDocument(b),a.html5=e})(this,document)