Tim reported some weirdness related to new parameter files in mform->validate(),

I can not reproduce it on my PHP 5.2, the is_validated is calling the validate() with two parameters now, maybe the problem is in method overriding

Tim could you please test following code snippet on your server that shows those errors/warnings:
<?php
require ('config.php');

class a {
    function go($c, $d) {
        echo "a: $c $d <br />";
    }
}

class b {
    function go($c) {
        echo "b: $c <br />";
    }
}

$a = new a();
$a->go(1, 2);

$b = new b();
$b->go(1, 2);

die;