DOMDocument loadHTML在Windows 7上无法正常工作

I'm facing a compatibility error between Mac Yosemith (10.10.4) and Windows 7 while trying to use the PHP function loadHTML of DOMDocument. Using Mac, everything works fine; using Windows, the Ajax function fails and goes automatically in the "error" part.

Here's the code of the Ajax function:

$('form').on("submit", function(event) {
        event.preventDefault(); // previene il comportamento di default ed esegue la chiamata ajax
        var uri = $("input[name='uri']").val();
        if (uri != '') {
            $.ajax({
                type : 'POST',
                url : 'SetFrame.php',
                headers : {'Content-Type':'application/x-www-form-urlencoded'},
               data : 'uri=' + uri,
                dataType : 'json',
                success : function (result) {
                    apriDocumento(result.title, result.url);
                },
                error : function(jqXHR, textStatus, errorThrown){
                    alert(jqXHR.status);
                    alert(jqXHR.status);
                    alert(jqXHR.responseText);
                }
            });
           } else {
            alert('Immetti qualcosa nel campo ricerca!')
        }

        $("input[name='uri']").prop('value', '');
    });

And here's the PHP code that answers the function:

<?php
    if(isset($_POST['uri'])) {
        $url = $_POST['uri'];
        $header = get_headers($url, 1);
        if(isset($header["X-Frame-Options"])) {
            echo 'Warning';
        } else {
            $doc = new DOMDocument();
            libxml_use_internal_errors(true);
            $doc->loadHTML($url);
            libxml_use_internal_errors(false);
            $xpath = new DOMXPath($doc);
            $titles = $xpath->query('//title/text()');

            foreach ($titles as $t) {
                $title = $t->nodeValue;
            }
            $data = array('title'=>$title, 'url'=>$url);
            echo json_encode($data);
        } }
?>

Any idea about the reason?