Index: vertical_tabs.module
===================================================================
--- vertical_tabs.module	(revision 2929)
+++ vertical_tabs.module	(working copy)
@@ -348,7 +348,8 @@
     // Track the maximum weight for the vertical tabs element.
     $weight = max($weight, $settings[$key]['weight']);
 
-    $settings[$key]['weight'] += 0.001 * $delta++;
+    $key_weight = $settings[$key]['weight'] * 1000;
+    $settings[$key]['weight'] = $key_weight + $delta++;
   }
 
   // The JavaScript and CSS specific for this form.