Erros em aplicações asp.net

beleza pessoal?Toda vez que baixo um codigo da algum site cujo web.config seta o modo de autenticação recebo a mensagem de erro abaixo.O que devo fazer para executar estes aplicativos corretamente? Alguma permissão especial no IIS?Obrigado.Server Error in '/' Application.--------------------------------------------------------------------------------Configuration Error Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. Parser Error Message: It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS.Source Error: Line 23: "Forms", "Passport" and "None"Line 24: -->Line 25: <authentication mode="Windows" /> Line 26: Line 27: Source File: c:\inetpub\wwwroot\menus\menu5\menu\web.config Line: 25