I'm getting a 500.19 error in IIS7 for a site I've set up locally. I've given IIS_IUSRS and even Everyone full control on the directory and reinstalled ASP.NET in IIS. I can't request any files - images etc, and I've spent so long looking for solutions and I'm not sure what else to try.
That error does not necessarily have anything to do with permissions. Have you viewed the details of the error?
Here's some info that should help: 500.19 is usually related to configuration errors.