Browsing to the site results in a 500 error, and nothing is logged to the
windows event log. Adding 'everyone full control' permission does not resolve
the issue, ruling out a permissions problem. In IIS, going to some of the
config areas of the site (e.g. modules) results in a nondescript "There was an
error while performing this operation" with the path to web.config and no
other details.

These symptoms occur when a site is using the URL Rewrite module -- install it
via Microsoft's Web Platform Installer, then restart IIS.