DateTime weirdness. When passing a timestamp to the constructor, if it's a Unix timestamp, you must prepend it with an @.

test.php

<?php
print_r(new DateTime('01/01/2012'));

/*
Good
DateTime Object
(
    [date] => 2012-01-01 00:00:00
    [timezone_type] => 3
    [timezone] => America/Chicago
)
*/

print_r(new DateTime(strtotime('01/01/2012')));

/*
Bad
DateTime Object
(
    [date] => 7600-05-07 13:25:39
    [timezone_type] => 3
    [timezone] => America/Chicago
)
*/

print_r(new DateTime('@' . strtotime('01/01/2012')));

/*
Finally Correct.
DateTime Object
(
    [date] => 2012-01-01 06:00:00
    [timezone_type] => 1
    [timezone] => +00:00
)
*/