--- popups_reference.module	2011-01-22 10:31:28.752124000 +0100
+++ popups_reference.module	2011-01-22 10:32:07.836124006 +0100
@@ -54,7 +54,7 @@ function popups_reference_form_alter(&$f
  *   to select the newly created node in the reference widget.
  */ 
 function popups_reference_nodeapi($node, $op) {
-  if ($op == 'insert') {
+  if ($op == 'insert' && !headers_sent()) {
     $five = time()+300; // 5 minutes in the future.
     setcookie("PopupRefNid", $node->nid, $five, '/'); 
     setrawcookie("PopupRefTitle", rawurlencode($node->title), $five, '/');