"Sites" is the parent object in IIS under which all the websites are located - Default Web Site, SBS Sharepoint, etc. I am honestly not sure why it has to resolve to the internal FQDN of the server. However, if OWA, RWW, Sharepoint, the company website, etc., IOW any internal or external sites you need, are working it sounds like that error message is bogus. Have you tried to access these resources and are they working?