[Adrian Schneider]

Try this to block registrations: hook: userdata_doset

PHP Code:

if (!isset($banBirthday))
{
    $banBirthday = array(
        'day' => 28,
        'month' => 3,
        'year' => 1983
    );
}

if ($fieldname == 'birthday' and $value === $banBirthday)
{
    exit;
} 


and to prevent them from posting more with the current accounts - hook: global_start

PHP Code:

if ($vbulletin->userinfo['birthday'] == '03-28-1983')
{
    exit;
} 


not tested, but im sure you could test it easily enough (create new acct).