ya solucione era que está sacando la IP con getIP()
y la ip no estaba definida
Código PHP:
function getIP(){
echo getenv('REMOTE_ADDR');
}
//do we have "remember me"?
if ( $remember ) {
setcookie ( "cookie_id", $user_id, time() + KEEP_LOGGED_IN_FOR, COOKIE_PATH );
setcookie ( "authenticate", md5 ( getIP () . $password . $_SERVER['USER_AGENT'] ), time() + KEEP_LOGGED_IN_FOR, COOKIE_PATH );
}
}