IIS não roda ASP.NET

Ola pessoal, Tento rodar asp.net com asp porem o servidor envia uma mensagem de erro "Server Application Unavailable The web application you are attempting to access on this web server is currently unavailable". Antes eu rodava normal. ele pede para ir no log e o log indica: "Failed to initialize the AppDomain:/LM/W3SVC/1/ROOT Exception: System.NullReferenceException Message: Object reference not set to an instance of an object. StackTrace: at System.Web.Hosting.HostingEnvironment.Initialize(Application Manager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) at System.Web.Hosting.ApplicationManager.CreateAppDomainWithHos tingEnvironment(String appId, IApplicationHost appHost, HostingEnvironmentParameters hostingParameters) at System.Web.Hosting.ApplicationManager.CreateAppDomainWithHos tingEnvironmentAndReportErrors(String appId, IApplicationHost appHost, HostingEnvironmentParameters hostingParameters) " Depois: "Failed to execute request because the App-Domain could not be created. Error: 0x80004003 Ponteiro inválido " Alguem sabe me explicar oque pode ser isso. Valew Galera.