Index: wp-includes/classes.php
===================================================================
--- wp-includes/classes.php	(revision 13170)
+++ wp-includes/classes.php	(working copy)
@@ -473,9 +473,10 @@
 	function handle_404() {
 		global $wp_query;
 
-		if ( (0 == count($wp_query->posts)) && !is_404() && !is_search() && ( $this->did_permalink || (!empty($_SERVER['QUERY_STRING']) && (false === strpos($_SERVER['REQUEST_URI'], '?'))) ) ) {
+		// if ( (0 == count($wp_query->posts)) && !is_404() && !is_search() && ( $this->did_permalink || (!empty($_SERVER['QUERY_STRING']) && (false === strpos($_SERVER['REQUEST_URI'], '?'))) ) ) {
+		if ( (0 == count($wp_query->posts)) && !is_404() && !is_search() && !is_home() ) {
 			// Don't 404 for these queries if they matched an object.
-			if ( ( is_tag() || is_category() || is_author() ) && $wp_query->get_queried_object() ) {
+			if ( ( is_tag() || is_category() || is_tax() || is_author() ) && $wp_query->get_queried_object() ) {
 				if ( !is_404() )
 					status_header( 200 );
 				return;