Index: units/orders/orders_event_handler.php
===================================================================
--- units/orders/orders_event_handler.php	(revision 13931)
+++ units/orders/orders_event_handler.php	(working copy)
@@ -3764,6 +3764,11 @@
 			$this->Conn->Query($sql);
 		}
 
+		if ( !is_object($event->MasterEvent) ) {
+			// not called as hook
+			return ;
+		}
+
 		$pre_expiration = adodb_mktime() + $this->Application->ConfigValue('User_MembershipExpirationReminder') * 3600 * 24;
 		$to_charge = $this->getRecurringOrders($pre_expiration);