Index: wp-login.php
===================================================================
--- wp-login.php	(revision 3964)
+++ wp-login.php	(working copy)
@@ -208,6 +208,8 @@
 				$error = __('Your session has expired.');
 		}
 	}
+	else if ( $user_login || $user_pass )
+		$error = __('<strong>Error</strong>: The password field is empty.');
 ?>
 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 <html xmlns="http://www.w3.org/1999/xhtml">

