Index: wp-settings.php
===================================================================
--- wp-settings.php	(revision 16754)
+++ wp-settings.php	(working copy)
@@ -15,6 +15,9 @@
  */
 define( 'WPINC', 'wp-includes' );
 
+// Start an output buffer in case anything generates warnings or notices before cookies are sent.
+ob_start();
+
 // Include files required for initialization.
 require( ABSPATH . WPINC . '/load.php' );
 require( ABSPATH . WPINC . '/default-constants.php' );
@@ -288,6 +291,9 @@
 // Set up current user.
 $wp->init();
 
+// Authentication cookies are now sent; safely release the output buffer started further up.
+ob_end_flush();
+
 /**
  * Most of WP is loaded at this stage, and the user is authenticated. WP continues
  * to load on the init hook that follows (e.g. widgets), and many plugins instantiate