I have an extremely simple implementation that pulls in a test bit of XML and attempts to validate it using DOMDocument. In testing, it's able to get through the LoadHTML() call fine, but as soon as I try and run validate(), the browser hangs forever and doesn't load. Here's the code:
$content = '<?xml version="1.0" encoding="utf-8"?><mainElement></mainElement>';
$dom = new DOMDocument;
$dom->LoadHTML($content);
if (!$dom->validate()) {
echo 'fail';
} else {
echo 'success!';
}