An application or a service that uses the NTLM authentication runs on a computer that is running Windows Server 2008 or Windows Vista. In this scenario, the memory usage of the Lsass.exe process keeps increasing. If this issue lasts for a long time, the application or the service may stop responding or encounter an exception because the available memory is too low.
For example, this issue occurs when a Web server uses NTLM for outgoing authentication. After this issue occurs, the Web server stops responding, and you must restart the server to recover from the issue.