Having trouble with Form Plugin in IE8

Having trouble with Form Plugin in IE8

I just discovered that all of the various instances where I am using jQuery Form Plugin are not working in IE8. Everything works peachy in Firefox, Opera, Chrome, and IE6 (yes really!). But in IE8, the "beforeSubmit" runs, but the "success" does not. 

I must be doing something wrong that is consistent across all of my jquery form code or the xml generated by my php but I have no idea what it is. I'm using jquery form in many different parts of my site to do different stuff and none of it works in IE8.

Instructions to reproduce:
Click on the Refresh button on the left under the Chatbox. The expected behavior is you'll see "Loading..." real quick and then it will disappear as it reloads the chatbox content. However, in IE8, the Loading appears but the content never comes. You are stuck with "Loading..." IE8 does not throw any errors.

JS:
  1. function jquery_load_chatbox_contents(chatbox_id){
  2. form = '#chatbox_form_'+chatbox_id;
  3. target = "#chatbox_view_"+chatbox_id;
  4. xmlFile = "http://www.paperdemon.com/chatbox/display.php";
  7. var options = {
  8. target: target,
  9. beforeSubmit: function(formData, jqForm){

  11. $(target).prepend('<div class="loading">Loading...</div>');
  12. return true;
  13. },
  14. success: function(responseXML, statusText){
  16. var message = $('display', responseXML).text(); 
  17. $(target).html(message);

  19. },
  20. dataType: 'xml', 
  21. url: xmlFile,
  22.         type: 'post',
  23.         resetForm: true
  24. };
  25. $(form).ajaxSubmit(options);
  26. }

My PHP generating the xml sends this header info if it's helpful:
  1. header("Content-Type: text/xml; charset=utf-8");

I don't see any useful data from IE8's developer toolbar either so I have no idea how to debug this. Any thoughts on how would be useful.

Any help would be greatly appreciated.