Index: rules.module
===================================================================
--- rules.module	(revision 446)
+++ rules.module	(working copy)
@@ -345,7 +345,7 @@
   $count = 0;
   foreach (element_children($element) as $key) {
     $element[$key] += array('#weight' => 0);
-    $element[$key]['#weight'] += $count / 1000;
+    $element[$key]['#weight'] = (int) $element[$key]['#weight'] + ($count / 1000);
     $count++;
   }
   uasort($element, "element_sort");