The most common cause of the HTTP 500.19 error in IIS 7 from my experience has been down to missing IIS Modules. This could be due to the module(s) are specified in the web.config as the configuration could of come from another server or workstation. Another alternative issue could be the module has been disable on the site level.
Here is an example, notice the lack of meaningful help.
The solution is to install the missing modules. Looking between the <system.webServer> should reveal the missing module(s) which are listed in the web.config.
From my personal experience this is likely to be either of the follow modules: