Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.755
diff -u -p -r1.755 node.module
--- modules/node/node.module	20 Dec 2006 08:06:20 -0000	1.755
+++ modules/node/node.module	22 Dec 2006 00:10:51 -0000
@@ -2049,7 +2049,9 @@ function node_form_add_preview($form) {
     drupal_validate_form($form['form_id']['#value'], $form);
     if (!form_get_errors()) {
       // We pass the global $form_values here to preserve changes made during form validation
-      $form['#prefix'] = node_preview((object)$form_values);
+      $preview = node_preview((object)$form_values);
+      // If the node form already has a #prefix, we must preserve it.
+      $form['#prefix'] = isset($form['#prefix']) ? $preview . $form['#prefix'] : $preview;
     }
   }
   if (variable_get('node_preview', 0) && (form_get_errors() || $op != t('Preview'))) {