[jQuery] $.ajax calls in firefox doesn't work

[jQuery] $.ajax calls in firefox doesn't work


Hi to all.
I have problem with $.ajax call with Firefox. At all other browsers
works fine(Opera, IE6,Chrome)
My code:
$.ajax({
        url : "statistic_json.php",
        type : "post",
        dataType : "json",
        success : function(data) {
            statistic_data = data.occupied;
        },
        complete : function() {
        },
        error : function(xhr, ajaxOptions, thrownError) {
            alert("error");
        },
        async : false
    });
Response from Firefox(taken from Firebug console):
<HTML>
<HEAD>
    <TITLE>400 Bad Request</TITLE>
</HEAD>
<BODY BGCOLOR=#FFFFFF>
    <H1>400 Bad Request</H1>
    Your browser sent a request that this server could not understand.
</BODY>
</HTML>
Response from other browsers(Opera,Chrome,IE6)
{"occupied":{"data":[[1.247868e+12,1],[1247954400000,1],
[1248040800000,1]],"label":"some label"}}
Firefox browser ver:
Mozilla/5.0 (Windows; U; Windows NT 5.1; pl; rv:1.9.0.13) Gecko/
2009073022 Firefox/3.0.13