Fixes bug mentioned here: http://drupal.org/comment/reply/300084?page=1#comment-3067620

diff -Nurp ../cck.orig/modules/content_multigroup/content_multigroup.admin.inc ./modules/content_multigroup/content_multigroup.admin.inc
--- ../cck.orig/modules/content_multigroup/content_multigroup.admin.inc	2010-06-09 11:42:54.000000000 -0500
+++ ./modules/content_multigroup/content_multigroup.admin.inc	2010-06-09 11:43:53.000000000 -0500
@@ -323,7 +323,7 @@ function content_multigroup_display_over
     if ($group['group_type'] != 'multigroup') {
       continue;
     }
-    $subgroup_settings = isset($group['settings']['multigroup']['subgroup']) ? $group['settings']['multigroup']['subgroup'] : array();
+    $subgroup_settings = isset($group['settings']['display']['settings']['multigroup']['subgroup']) ? $group['settings']['display']['settings']['multigroup']['subgroup'] : array();
 
     $subgroup_name = $group_name .'_subgroup';
     $form['#fields'] = array_merge(array($subgroup_name), $form['#fields']);
@@ -373,22 +373,14 @@ function content_multigroup_display_over
 
       // We have some numeric keys here, so we can't use array_merge.
       foreach ($values as $k => $v) {
-        $group['settings']['multigroup']['subgroup'][$k] = $v;
+        $form_state['values'][$group_name]['settings']['multigroup']['subgroup'][$k] = $v;
       }
 
-      // Update the group information in the database. Note that
-      // 'fieldgroup_data' in cache tables are also cleared here,
-      // but we need to reset static caches of fieldgroup_groups().
-      fieldgroup_save_group($form['#type_name'], $group);
-      $reset_cache = TRUE;
-
       // Remove the subgroup from $form_state.
       unset($form_state['values'][$key]);
     }
   }
-  if ($reset_cache) {
-    fieldgroup_groups('', FALSE, TRUE);
-  }
+
 }
 
 /**