tikiwiki error

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000] [2000] mysqlnd cannot connect to MySQL 4.1+ using the old insecure authentication. Please use an administration tool to reset your password with the command SET PASSWORD = PASSWORD('your_existing_password'). This will store a new, and more secure, hash value in mysql.user. If this user is used in other scripts executed by PHP 5.2 or earlier you might need to remove the old-passwords flag from your my.cnf file' in /home/warriorc/public_html/tiki-check.php:177 Stack trace: #0 /home/warriorc/public_html/tiki-check.php(177): PDO->__construct('mysql:host=loca...', 'warriorc_tikiu2', '2warriortiki2') #1 {main} thrown in /home/warriorc/public_html/tiki-check.php on line 177