Access is denied error

I am having a problem in javascript.It is giving me access is denied error on internet explorer and I am unable to move to my next page.Here is the javascript code.

stuHover = function() {

    var cssRule;

    var newSelector;

    for (var i = 0; i < document.styleSheets.length; i++)

        for (var x = 0; x < document.styleSheets[i].rules.length ; x++)

            {

            cssRule = document.styleSheets[i].rules[x];

            if (cssRule.selectorText.indexOf("LI:hover") != -1)

            {

                 newSelector = cssRule.selectorText.replace(/LI:hover/gi, "LI.iehover");

                document.styleSheets[i].addRule(newSelector , cssRule.style.cssText);

            }

        }

    var getElm = document.getElementById("nav").getElementsByTagName("LI");

    for (var i=0; i<getElm.length; i++) {

        getElm[开发者_如何学Ci].onmouseover=function() {

            this.className+=" iehover";

        }

        getElm[i].onmouseout=function() {

            this.className=this.className.replace(new RegExp(" iehover\\b"), "");

        }

    }

}

if (window.attachEvent) window.attachEvent("onload", stuHover);

And the line on which it is saying error is coming

<div style="_margin-bottom:15px">
<div class="logo">

Thanks in advance