Hi All, Thank you for advance. I created a widows service for mail schedule with c#.net and sql server 2005 and it is working fine for past one year. now sometimes i am getting the "System.Data.SqlClient.SqlException: Login failed for user '<UserName>'. Reason: The account is disabled." error. then i restarted the windows service manually and working. what is the problem in my sql server connection and how to fix that issue?