--- node.module.orig	2009-02-16 09:39:40.000000000 -0500
+++ node.module	2009-06-11 16:05:27.000000000 -0400
@@ -1227,7 +1227,7 @@
       }
       if ($weight = (int)variable_get('node_rank_recent', 5)) {
         // Exponential decay with half-life of 6 months, starting at last indexed node
-        $ranking[] = '%d * POW(2, (GREATEST(MAX(n.created), MAX(n.changed), MAX(c.last_comment_timestamp)) - %d) * 6.43e-8)';
+        $ranking[] = '%d * POW(2, (GREATEST(MAX(n.created), MAX(n.changed), MAX(c.last_comment_timestamp) || 1) - %d) * 6.43e-8)';
         $arguments2[] = $weight;
         $arguments2[] = (int)variable_get('node_cron_last', 0);
         $join2 .= ' LEFT JOIN {node_comment_statistics} c ON c.nid = i.sid';