--- quicktabs/js/quicktabs.js	2010-08-31 14:56:28.000000000 -0700
+++ quicktabs/js/quicktabs.js	2010-08-31 14:53:31.000000000 -0700
@@ -89,6 +89,7 @@ Drupal.quicktabs.tab.prototype.stopProgr
     $(this.progress.element).remove();
   }
   $(this.element).removeClass('progress-disabled').attr('disabled', false);
+  $(this.element).parents('.quicktabs_wrapper').removeClass('working'); // remove lock
 }
 
 Drupal.quicktabs.tab.prototype.startProgress = function () {
@@ -159,6 +160,13 @@ var quicktabsClick = function() {
   }
   else {
     if ($(this).hasClass('qt_ajax_tab')) {
+      var qtWrapper = $(this).parents('.quicktabs_wrapper');
+
+      if (qtWrapper.hasClass('working')) {
+        return false; // already working (locked)
+      }
+      qtWrapper.addClass('working'); // go work (lock)
+
       tab.startProgress();
       // Construct the ajax tabpage.
       if (tab.tabObj.type != 'view') {