vb.net – App.config连接字符串保护错误

这是问题所在.我们使用以下代码为客户端应用程序加密app.config中的连接字符串部分：

config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None)
        If config.ConnectionStrings.SectionInformation.IsProtected = False Then
            config.ConnectionStrings.SectionInformation.ProtectSection(Nothing)

            ' We must save the changes to the configuration file.'
            config.Save(ConfigurationSaveMode.Modified,True)
        End If

问题是我们有一个营业员休假.旧的笔记本电脑将转到新的销售人员,并在新用户的登录下,当它试图这样做时,我们得到一个错误.错误是：

Unhandled Exception: System.Configuration.ConfigurationErrorsException: 
An error occurred executing the configuration section handler for connectionStrings. ---> System.Configuration.ConfigurationErrorsException: Failed to encrypt the section 'connectionStrings' using provider 'RsaProtectedConfigurationProvider'. 
Error message from the provider: Object already exists.
---> System.Security.Cryptography.CryptographicException: Object already exists