ajax check name

ajax check name

Hello,
 
I have the following code to check if a username existes. In my IDE it crashes and in the Browsers, It shows the returned html for a second and the goes away, and the page goes back to the top. Since it does come back correctly , I know it is working on one level.
$("#addNew").submit(function (){
   
    $("#UserExists").hide();
    var text = $('#username').val();
   
    var textlength = text.length;
    if(textlength>2)
{
    var name = $('#username').val();
    var data = 'username='+name;
    $.ajax({
        type:"POST",
        url:"CheckName.php",
        data:data,
        async: false,
        success:function(html){
            if(html=="That Username is already in use")
                {                  
                    x=2;
                    $("#UserExists").show();
                    $("#UserExists").text(html);
                   
                }
        }
        });
}
if(x==2)
 {
return false;



























}
});
 
 
Any Help?
Thanks
Mike