Index: uc_order.module
===================================================================
--- uc_order.module	(revision 2172)
+++ uc_order.module	(working copy)
@@ -1455,7 +1455,7 @@
   foreach (module_list() as $module) {
     $function = $module .'_order';
     // $order must be passed by reference.
-    if (function_exists($function) && ($value = $function('total', $order, NULL))) {
+    if (function_exists($function) && ($value = $function('total', $order, NULL)) && is_numeric($value)) {
       $total += $value;
     }
   }