We are running Moodle 1.9.6+ on a Windows 2003 box and we have been authenticating users against Active Directory for a few months. However, we do have an issue where a few of our users (approximately 5%) are not able to login to Moodle with their AD username and password - their AD password is rejected. They are able to login to our other systems with the same AD username and password. Most other users are able to login to Moodle without any problems. We haven't picked up anything unusal in the AD logs. And the problem persists even after we reset their AD password.
Does Moodle have an option to log any authentication errors that are generated when user authentication fails (using AD or any other authentication method)?