It seems like you're running an SQL server on your computer. If you have no use for it, uninstall it or disable it from starting every time Windows start. You might also want to run "services.msc" (without the quotes) from the "Run" command and check if you have an SMTP service. If that service is "stopped" or "disabled", double click on it to enable "start" it and change its "startup type" to "automatic"
Keep in mind that if you disable or uninstall your SQL server software, you don't need this service.
Also check this out.http://www.dotnetspider.com/forum/182756-The-server-response-was-5.5.1-Authentication-Required.aspx