Index: branches/unlabeled/unlabeled-1.57.2/core/kernel/session/session.php
===================================================================
diff -u -r8233 -r8234
--- branches/unlabeled/unlabeled-1.57.2/core/kernel/session/session.php	(.../session.php)	(revision 8233)
+++ branches/unlabeled/unlabeled-1.57.2/core/kernel/session/session.php	(.../session.php)	(revision 8234)
@@ -272,7 +272,8 @@
 	function StorePersistentVar(&$session, $var_name, $var_value)
 	{
 		$user_id = $session->RecallVar('user_id');
-		if ($user_id == -2) {
+		if ($user_id == -2 || $user_id === false) {
+			// -2 (when not logged in), false (when after u:OnLogout event)
 			return ;
 		}