foreach (XmlNode node in doc.SelectNodes("/users/user"))
            {

                String Username = node.SelectSingleNode("UserID").InnerText;
                String Password = node.SelectSingleNode("Password").InnerText;
                Password = encode(textBox7.Text);

                if (Username == comboBox1.SelectedItem.ToString() && Password == decode(textBox7.Text))
                {
                    DialogResult = DialogResult.OK;
                }