Index: wp-includes/cron.php
===================================================================
--- wp-includes/cron.php	(revision 3635)
+++ wp-includes/cron.php	(working copy)
@@ -49,7 +49,7 @@
 }
 
 function wp_clear_scheduled_hook($hook) {
-	while($timestamp = next_scheduled($hook))
+	while($timestamp = wp_next_scheduled($hook))
 		wp_unschedule_event($timestamp, $hook);
 }