diff --git a/wp-admin/admin.php b/wp-admin/admin.php
index 2c216386dd..f8405f9a09 100644
--- a/wp-admin/admin.php
+++ b/wp-admin/admin.php
@@ -146,7 +146,7 @@ if (isset($plugin_page)) {
 
 	// Make sure rules are flushed
 	global $wp_rewrite;
-	$wp_rewrite->flush_rules();
+	$wp_rewrite->flush_rules(false);
 
 	exit();
 } else {
diff --git a/wp-admin/includes/misc.php b/wp-admin/includes/misc.php
index d020e74add..b717f65a52 100644
--- a/wp-admin/includes/misc.php
+++ b/wp-admin/includes/misc.php
@@ -72,7 +72,9 @@ function insert_with_markers( $filename, $marker, $insertion ) {
 			$markerdata = explode( "\n", implode( '', file( $filename ) ) );
 		}
 
-		$f = fopen( $filename, 'w' );
+		if ( !$f = @fopen( $filename, 'w' ) )
+			return false;
+
 		$foundit = false;
 		if ( $markerdata ) {
 			$state = true;
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 407b33c576..0c0ba46d6d 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -1192,7 +1192,7 @@ function wp_delete_post($postid = 0) {
 		foreach ( (array) $children as $child )
 			clean_page_cache($child->ID);
 
-		$wp_rewrite->flush_rules();
+		$wp_rewrite->flush_rules(false);
 	} else {
 		clean_post_cache($postid);
 	}
@@ -3354,7 +3354,7 @@ function _save_post_hook($post_id, $post) {
 		// Avoid flushing rules for every post during import.
 		if ( !defined('WP_IMPORTING') ) {
 			global $wp_rewrite;
-			$wp_rewrite->flush_rules();
+			$wp_rewrite->flush_rules(false);
 		}
 	} else {
 		clean_post_cache($post_id);
diff --git a/wp-includes/rewrite.php b/wp-includes/rewrite.php
index c84b5205ed..3486c4a5b4 100644
--- a/wp-includes/rewrite.php
+++ b/wp-includes/rewrite.php
@@ -1822,13 +1822,14 @@ class WP_Rewrite {
 	 *
 	 * @since 2.0.1
 	 * @access public
+	 * @param $hard bool Whether to update .htaccess (hard flush) or just update rewrite_rules transient (soft flush). Default is true (hard).
 	 */
-	function flush_rules() {
+	function flush_rules($hard = true) {
 		delete_transient('rewrite_rules');
 		$this->wp_rewrite_rules();
-		if ( function_exists('save_mod_rewrite_rules') )
+		if ( $hard && function_exists('save_mod_rewrite_rules') )
 			save_mod_rewrite_rules();
-		if ( function_exists('iis7_save_url_rewrite_rules') )
+		if ( $hard && function_exists('iis7_save_url_rewrite_rules') )
 			iis7_save_url_rewrite_rules();
 	}