We have seen this in our environment historically and are trying to eradicate. recently, we had a big flurry of these errors. It is almost impossible to reproduce .. an exception gets thrown, "the server is not operational" and here is the code dirConn.DirRootAD.Username = ConvertToCorrectUserNameFormat(sUserName, ADConnManager.Domain) dirConn.DirRootAD.Password = Password dirConn.DirRootAD.AuthenticationType = AuthenticationTypes.ServerBind mySearcher.Filter = "(&(objectCategory=user)(|(sAMAccountName=" + sUserName + ")(userPrincipalName=" + sUserName + ")))" dirConn.DirRootAD = mySearcher.FindOne().GetDirectoryEntry() .... Finally If Not objDirEntry Is Nothing Then objDirEntry.Dispose() If Not dirConn Is Nothing Then dirConn.Dispose() I hear this may be due to a BUG in the .NET framework? any truth to that? Any suggestions would be helpful.