Problem with loading and autorefreshing div with IE7-8

Problem with loading and autorefreshing div with IE7-8

Hi,

I have a function count_new_messages which returns a string like 'you have (2) messages'
  1. <script>
    var auto_refresh = setInterval(
    function()
    {
    $('#show_new_messages').fadeOut('slow').load("<?=base_url()?>ajax/count_new_messages").fadeIn("slow");
    }, 3000);
    </script>

    <div id="show_new_messages"></div>








And the problem is, that it's not working properly with IE7-8.

Any ideas?

Thanks in advance.