Index: nodereference_url.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/nodereference_url/nodereference_url.module,v
retrieving revision 1.18
diff -u -r1.18 nodereference_url.module
--- nodereference_url.module	7 Jan 2010 04:58:47 -0000	1.18
+++ nodereference_url.module	7 Jan 2010 05:12:51 -0000
@@ -336,6 +336,12 @@
 
   // If no NID is available, use the fallback behavior.
   if (!isset($referenced_nid)) {
+    // If not on a node/add page (such as editing a node that does not yet have
+    // a reference), switch to using an autocomplete widget.
+    if ($field['widget']['fallback'] == 'page_not_found' && arg(0) == 'node' && is_numeric(arg(1))) {
+      $field['widget']['fallback'] = 'autocomplete';
+    }
+
     // Page not found error.
     // Check for the form_build_id to prevent throwing a page not found on
     // manual builds. See http://drupal.org/node/397606.