The bug described here is present in RHEL 6.2 php 5.3.3:
https://bugs.php.net/bug.php?id=53551

Description:
------------
A segfault will occur when a PDOStatement is reused after failing due to a NOT 
NULL integrity constraint.  This occurred when using the pdo_mysql driver as 
opposed to the mysqlnd driver.

Also to avoid confusion, I was only able to test this on PHP 5.3.2.  I could find 
nothing in the changelogs that would imply this bug has been fixed.  I 
unfortunately did not have the time to free up hardware or vms for an upgrade.

Test script:
---------------
$dbh = new PDO('mysql:host=127.0.0.1;dbname=foo', 'user', 'pass');
$dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, 0);

$createSql = "CREATE TABLE `foo` (
  `count` bigint(20) unsigned NOT NULL DEFAULT '0'
)";

$dbh->exec('drop table if exists foo');
$dbh->exec($createSql);
$dbh->exec("insert into foo set `count` = 1 ");

$sql = 'UPDATE foo SET `count` = :count';
$stmt = $dbh->prepare($sql);

$values = array (
  'count' => NULL,
);

echo "1\n";
$stmt->execute($values);
var_dump($stmt->errorInfo());

echo "2\n";
$stmt->execute($values);
var_dump($stmt->errorInfo());

echo "\ndone\n";


Expected result:
----------------
[ed@foo ~]$ php ed.php
1
array(3) {
  [0]=>
  string(5) "23000"
  [1]=>
  int(1048)
  [2]=>
  string(29) "Column 'count' cannot be null"
}
2
array(3) {
  [0]=>
  string(5) "23000"
  [1]=>
  int(1048)
  [2]=>
  string(29) "Column 'count' cannot be null"
}
done


Actual result:
--------------
[ed@foo ~]$ php ed.php
1
array(3) {
  [0]=>
  string(5) "23000"
  [1]=>
  int(1048)
  [2]=>
  string(29) "Column 'count' cannot be null"
}
2
Segmentation fault