diff -rup ubercart_old/uc_cart/uc_cart_checkout_pane.inc ubercart/uc_cart/uc_cart_checkout_pane.inc
--- ubercart_old/uc_cart/uc_cart_checkout_pane.inc	2010-10-27 14:12:22.000000000 +0100
+++ ubercart/uc_cart/uc_cart_checkout_pane.inc	2010-11-07 12:10:04.000000000 +0000
@@ -486,7 +486,7 @@ function _uc_cart_checkout_prev_pane($pa
     if ($target['id'] == $pane_id) {
       return $prev;
     }
-    if ($target['collapsible'] && variable_get('uc_pane_'. $target['id'] .'_enabled', TRUE)) {
+    if ($target['collapsible'] && $target['enabled']) {
       $prev = $target['id'];
     }
   }
@@ -505,7 +505,7 @@ function _uc_cart_checkout_next_pane($pa
   $next = FALSE;
   foreach ($panes as $target) {
     if ($next) {
-      if ($target['collapsible'] && variable_get('uc_pane_'. $target['id'] .'_enabled', TRUE)) {
+      if ($target['collapsible'] && $target['enabled']) {
         return $target['id'];
       }
     }
@@ -528,12 +528,20 @@ function _checkout_pane_list($action = N
   }
 
   $panes = module_invoke_all('checkout_pane', NULL);
-  // Allow other modules to alter the panes.
-  drupal_alter('checkout_pane', $panes);
-
+  
+  // Set the global default values first
   foreach ($panes as $i => $value) {
     $panes[$i]['enabled'] = variable_get('uc_pane_'. $panes[$i]['id'] .'_enabled', (!isset($panes[$i]['enabled']) ? TRUE : $panes[$i]['enabled']));
     $panes[$i]['weight'] = variable_get('uc_pane_'. $panes[$i]['id'] .'_weight', (!isset($panes[$i]['weight']) ? 0 : $panes[$i]['weight']));
+  }
+  
+  // Allow other modules to alter the panes.
+  drupal_alter('checkout_pane', $panes);
+  
+  // Make sure that all the required attributes are set
+  foreach ($panes as $i => $value) {
+    $panes[$i]['enabled'] = !isset($panes[$i]['enabled']) ? TRUE : $panes[$i]['enabled'];
+    $panes[$i]['weight'] = !isset($panes[$i]['weight']) ? 0 : $panes[$i]['weight'];
     $panes[$i]['review'] = !isset($panes[$i]['review']) ? TRUE : $panes[$i]['review'];
     $panes[$i]['process'] = !isset($panes[$i]['process']) ? TRUE : $panes[$i]['process'];
     $panes[$i]['collapsible'] = !isset($panes[$i]['collapsible']) ? TRUE : $panes[$i]['collapsible'];
diff -rup ubercart_old/uc_cart/uc_cart.pages.inc ubercart/uc_cart/uc_cart.pages.inc
--- ubercart_old/uc_cart/uc_cart.pages.inc	2010-09-02 14:44:39.000000000 +0100
+++ ubercart/uc_cart/uc_cart.pages.inc	2010-11-07 12:05:01.000000000 +0000
@@ -160,7 +160,7 @@ function uc_cart_checkout_form() {
   }
 
   foreach ($panes as $pane) {
-    if (variable_get('uc_pane_'. $pane['id'] .'_enabled', $pane['enabled'])) {
+    if ($pane['enabled']) {
       $pane['prev'] = _uc_cart_checkout_prev_pane($panes, $pane['id']);
       $pane['next'] = _uc_cart_checkout_next_pane($panes, $pane['id']);
 
@@ -377,7 +377,7 @@ function uc_cart_checkout_review() {
   }
 
   foreach ($panes as $pane) {
-    if (variable_get('uc_pane_'. $pane['id'] .'_enabled', TRUE)) {
+    if ($pane['enabled']) {
       $func = $pane['callback'];
       if (function_exists($func)) {
         $return = $func('review', $order, NULL);