I have some jQuery AJAX calls that work fine on Safari, Chrome, and Opera but doesn't seem to get through with Firefox. Has anyone run into this or is there some setting in Firefox that could be interfering? 

function postRequest (req) {
    return $.ajax({
        type: 'POST',
        url: vibe + '/process_req',
        data: JSON.stringify(req),
        contentType: 'application/json',
        dataType: 'text'
    });
}