function getXmlHttpRequestObject() {
 if (window.XMLHttpRequest) {
    return new XMLHttpRequest(); //Mozilla, Safari ...
 } else if (window.ActiveXObject) {
    return new ActiveXObject("Microsoft.XMLHTTP"); //IE
 } else {
    alert("Your browser doesn't support the XmlHttpRequest object.");
    return false;
 }
}

var receiveReq2 = getXmlHttpRequestObject();

function makeRequest2(url, param) {
 if (receiveReq2.readyState == 4 || receiveReq2.readyState == 0) {

   receiveReq2.open("POST", url, true);
   receiveReq2.onreadystatechange = updatePage2; 

   receiveReq2.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
   receiveReq2.setRequestHeader("Content-length", param.length);
   receiveReq2.setRequestHeader("Connection", "close");

   receiveReq2.send(param);
 }   
}

function updatePage2() {
 if (receiveReq2.readyState == 4) {
   //document.getElementById('renovar').innerHTML = '<a tabindex=-1 href="#" onclick="getParam2();"><span class="otrai">Solicitar otra imagen</span></a>';
   document.getElementById('captcha').style.display = "inline";
 }
}

function getParam2() {
 var url = 'captcha_create.php';
 postStr = '';
// document.getElementById('renovar').innerHTML = "<center>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<img src='images/reloading_captcha.gif'></center>";
// document.getElementById('captcha').style.display = "none";
 document.getElementById('captcha').innerHTML = '<img id="imgCaptcha" src="create_image.php?' + Math.random() + '">';
// makeRequest2(url, postStr);
}