Try updating this:
<?php if (isset($_POST['Confirm']) && $WADAlogins->getColumnVal("UserPassword") != $_POST['Confirm']) {
$_SESSION['PasswordChanged'] = true;
} ?>
to this:
<?php if (isset($_POST['Confirm']) && $WADAlogins->getColumnVal("UserPassword") != $_POST['Confirm']) {
@session_start();
$_SESSION['PasswordChanged'] = true;
session_commit();
} ?>
The new DataAssist code is "better" about closing the session when it isn't being used since leaving the session open can cause delays in asynchronous page requests such as AJAX. What that means is that the session might be closed after use automatically and needs to be re-started before a new variable can be stored.