500 Internal Server Error” when adding HttpModule in my Web.config

use the following new module syntax made for IIS7 (godaddy is using IIS7 for windows hosting)

<configuration>
   <system.webServer>
      <modules>
         <add name="Header" type="Contoso.ShoppingCart.Header"/>
      </modules>
   </system.webServer>
</configuration>

here details about module tag  

Login failed for user 'IIS APPPOOL\ASP.NET v4.0'

Set Identity : LocalSystem


You can change the ApplicationPoolIdentity from IIS7 -> Application Pools -> Advanced Settings.