ajax请求强制浏览器重新加载

I'm pretty new to ajax.

I try to load some data with Ajax and PHP. That basically works without any problems, but there is always a refresh bar when the Ajax updates are executed (in Firefox, Chrome).

The page isn't really refreshing entirely but every two seconds a refresh bar appears (and that gets really annoying): http://i.stack.imgur.com/IZ5XY.png

Code:

main.js:

    window.onload = function onLoad() {
        setInterval("reload()",2000);
    };
.
.
.
        function reload() {
             $.ajax({
                type: "GET",
                url: "script.php",
                success: function(msg){
                    $("#test").text("txt");
                }
            });
        }

The php Script just echos some txt!

Every help is appricated, Thank You! Kind Regards