Ajax xmlhttp request problem

I'm having a curious problem, at least it's curious for me.. that when a start a download on my website, ajax functions stop working, only after the donwload stops, the functions work.
I'm going to show some parts of my code.

downloadfile.php

$fileType = $_GET['tipo'];
$fileSize = $_GET['tamanho'];
$fileContent = $b;
$fileName = $_GET['nome'];

// fix for IE catching or PHP bug issue
header("Pragma: public");
header("Expires: 0"); // set expiration time
header("Cache-Control: no-cache, must-revalidate, post-check=0, pre-check=0");
// browser must download file from server instead of cache

header("Content-Description: File Transfer");
header("Content-type: $fileType");
header("Content-Length: ".filesize($fileSize));
header("Content-Disposition: attachment; filename=\"".$fileName."\"");

flush();
//for files bigger than 100megabytes
$fp = fopen($fileContent, "r");
while (!feof($fp)){
echo fread($fp, 65536);
flush(); // this is essential for large downloads
}
fclose($fp);

and then my ajax script

response.js

function ajaxAbre(pagina,id){
var xmlHttp;
try {
// Firefox, Opera 8.0+, Safari
xmlHttp=new XMLHttpRequest();
}
catch (e) {
// Internet Explorer
try {
xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e){
try {
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e) {
alert("Seu navegador não suporta AJAX. Atualize-o em www.getfirefox.com");
return false;
}
}
}

xmlHttp.onreadystatechange=function() {
if(xmlHttp.readyState == 1) {
document.getElementById(id).innerHTML = "Carregando...<img src='./images/loading.gif'></img>";
}
if(xmlHttp.readyState == 4) {
document.getElementById(id).innerHTML = xmlHttp.responseText;

}
}
xmlHttp.open("GET",pagina,true);
xmlHttp.send(null);
}

ajax code in my website works to change content in certain divs

thanks already! hope someone understand my needs :P

What browser is it happening in?

With Internet Explorer, it is limited to two open connections to a domain. The download will clog the one connection leaving the other one open. When the download completes you have two connections.

So you should try using a sub domain/ CName for your download.

Eric

I'm testing on Safari, Mozilla and Opera. They all behave the same, let me waiting for the download to finish, then ajax code works. And i'm sorry , can you explain with an example what you said before?

Hey if you haven't already solved your problem I may be able to help. I've had problems with Ajax for months with it working in some places and not others so I tried to find a good javascript library to standardise how I use. I would recommend you either use a javascript library such as YUI or jQuery or use a javascript class like the one on this site www.dev-explorer.com/articles/ajax-request-class. I personally prefer to use straight javascript as opposed to frameworks but its up to you.

Hope this helps
@pple