I am running a trial of Exchange and just set the server up. Email working fine with it, but I cannot access the webpages for the Exchange Control Panel or the OWA website. I get a 500 Error even from trying to open the URL on the server itself.
Exchange 2010 SP2 installation identified features that were not active in IIS. Once these features were added to IIS, the OWA and ECP pages worked correctly.