Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 12955)
+++ wp-includes/user.php	(working copy)
@@ -86,7 +86,7 @@
 	$userdata = get_user_by('login', $username);
 
 	if ( !$userdata )
-		return new WP_Error('invalid_username', sprintf(__('<strong>ERROR</strong>: Invalid username. <a href="%s" title="Password Lost and Found">Lost your password</a>?'), site_url('wp-login.php?action=lostpassword', 'login')));
+		return new WP_Error('invalidcombo', sprintf(__('<strong>ERROR</strong>: Incorrect username or password. <a href="%s" title="Password Lost and Found">Lost your password</a>?'), site_url('wp-login.php?action=lostpassword', 'login')));
 
 	if ( is_multisite() ) {
 		// Is user marked as spam?
@@ -106,7 +106,7 @@
 		return $userdata;
 
 	if ( !wp_check_password($password, $userdata->user_pass, $userdata->ID) )
-		return new WP_Error('incorrect_password', sprintf(__('<strong>ERROR</strong>: Incorrect password. <a href="%s" title="Password Lost and Found">Lost your password</a>?'), site_url('wp-login.php?action=lostpassword', 'login')));
+		return new WP_Error('invalidcombo', sprintf(__('<strong>ERROR</strong>: Incorrect username or password. <a href="%s" title="Password Lost and Found">Lost your password</a>?'), site_url('wp-login.php?action=lostpassword', 'login')));
 
 	$user =  new WP_User($userdata->ID);
 	return $user;
Index: wp-login.php
===================================================================
--- wp-login.php	(revision 12955)
+++ wp-login.php	(working copy)
@@ -572,7 +572,7 @@
 	login_header(__('Log In'), '', $errors);
 
 	if ( isset($_POST['log']) )
-		$user_login = ( 'incorrect_password' == $errors->get_error_code() || 'empty_password' == $errors->get_error_code() ) ? esc_attr(stripslashes($_POST['log'])) : '';
+		$user_login = ( 'empty_password' == $errors->get_error_code() ) ? esc_attr(stripslashes($_POST['log'])) : '';
 ?>
 
 <?php if ( !isset($_GET['checkemail']) || !in_array( $_GET['checkemail'], array('confirm', 'newpass') ) ) : ?>