Odd error from script in header

[SBlueman]

This script which is in my header include template is this:

<script type="text/javascript">

Array.prototype.contains = function (ele) {
    for (var i = 0; i < this.length; i++) {
        if (this[i] == ele) {
            return true;
        }
    }
    return false;
};

Array.prototype.remove = function (ele) {
    var arr = new Array();
    var count = 0;
    for (var i = 0; i < this.length; i++) {
        if (this[i] != ele) {
            arr[count] = this[i];
            count++;
        }
    }
    return arr;
};

window.onload = function () {
        var taglist = document.getElementById('tags');
	taglist.value = taglist.value.replace (/\s+/g,'');  // strip space
        var tags = taglist.value.split(',');
        
        var populartags = document.getElementById('popularTags').getElementsByTagName('span');
        
        for (var i = 0; i < populartags.length; i++) {
            if (tags.contains(populartags[i].innerHTML)) {
                populartags[i].className = 'selected';
            }
        }
}

function doTag(ele) {
    var thisTag = ele.innerHTML;
    var taglist = document.getElementById('tags');
    var tags = taglist.value.split(',');
 
    // If tag is already listed, remove it
    if (tags.contains(thisTag)) {
        tags = tags.remove(thisTag);
        ele.className = 'unselected';
        
    // Otherwise add it
    } else {
        tags.splice(tags.length-1, 0, thisTag);
        ele.className = 'selected';
    }
    
    taglist.value = tags.join(',');
    document.getElementById('tags').focus();
}
</script>

I have to have this code because it is key to critical feature on the site. Unfortunately it seems to be causing some issues to my message editor. When I go to select a font or font size, I am getting this odd link at the bottom of my font drop-down:



I am also getting an error with the font size drop-down menu:


Is there a way to isolate the script and have it called from somewhere else other than the template and would this fix the template error I am experiencing?

Also....and I don't know if this is related.....

I am getting this error when selecting threads:



I have two checked.....and the counter says four. I uncheck them, and the number changes. It's acting all squirrelly.