Description:
------------
PHP crash by using the DOM function getElementById() (PHP kill the Apache server process on Windows, with Apache v1.3.27 and v2.0.48).

Reproduce code:
---------------
<?php
$dom = new DomDocument;
$dom -> load('essai.xml');

if ($dom -> validate()) {
	$menu = new DomDocument;
	$menu = $dom -> getElementById('a');
	echo $menu -> firstChild -> data;
}
?>

essai.xml :
-----------

<?xml version="1.0"?>
<!DOCTYPE essai [
	<!ELEMENT essai (truc+)>

	<!ELEMENT truc (#PCDATA)>
	<!ATTLIST truc
		id	ID		#REQUIRED>
]>

<essai>
	<truc id="a">1</truc>
</essai>

Expected result:
----------------
1

Actual result:
--------------
Nothing, PHP and the server crash...
There is the same result with an external doctype.
When I call getElementById(id) with an id who doesn't exist in the XML file, there is no crash.