Solution to Free tetbox error while using update panel

 <script language="javascript" type="text/javascript">
    function FTB_RemoveEvent(obj, evType, fn, useCapture) {
    if (useCapture==undefined) useCapture=true;

    try
    {
        if (obj.removeEventListener) {
            obj.removeEventListener(evType, fn, useCapture);
        } else if (obj.detachEvent) {
        obj.detachEvent('on' + evType, fn);
    }

    }
    catch(err) {   
               }
    };
    FTB_RemoveEvent("FreeTextBoxName","onload","","");
    </script>