jQuery POST to PHP hangs, causing unresponsive page

I have the following JavaScript on my page:

$('#report_submit').click(function(event){
    event.preventDefault();
    if ( $('#email').val() == "" )
    {
        reportmessage('Please enter an e-mail address.');
        return false;
    }
    $.post('report.php',{method:reported,email:$开发者_JS百科('#email').val()},function(data){
        if (data == 'error')
        {
            reportmessage('Catastrophic failure. Please try again.');
        }
        if (data == 'email')
        {
            reportmessage('Check your e-mail address and try again.');
        }
        if (data == 'success')
        {
            $('#reportform').fadeOut();
            $('#reportsuccess').fadeIn();
            return true;
        }
    });
});

And report.php:

<?php

if ($_SERVER['REQUEST_METHOD'] == 'POST')
{
    // Server side verification
    $method = trim(strip_tags(stripslashes($_POST['method'])));
    $email = trim(strip_tags(stripslashes($_POST['email'])));

    if (empty($method) OR empty($email))
    {
        echo 'error';
        exit;
    }

    if (filter_var($email, FILTER_VALIDATE_EMAIL) === false)
    {
        echo 'email';
        exit;
    }

    // Write it to the log
    $data = date('c').' - '.$_SERVER['REMOTE_ADDR'].' - '.$email.' - '.$method."\n";

    file_put_contents ( 'reports.txt', $data, FILE_APPEND );

    echo 'success';
    exit;
}

?>

When the submit button is clicked, and there is a value in the e-mail address textfield, the page freezes almost instantly. I have to close/kill the process and reload the page. The JavaScript console shows nothing. I would assume the PHP script is running just fine; if I replace the script with echo 'error'; the page works and I get the catastrophic error message. However, passing the POST variables directly to the script and not through AJAX shows the correct output in the browser.

It can't be a PHP issue, and the JavaScript should work fine (and does, when the PHP script returns a simple value without doing anything else). I've tested this page on my Mac in Chrome and Firefox, and on Windows in Firefox, Chrome, and IE. All freeze.

Is this a server configuration issue, and if so, what should I look for or change?