i recently installed SBS 2k3, i have a domain with exchange set up and 10 users. When i get the email every morning at 6am with the server performance report it just says:
Server Application Unavailable
The web application you are attempting to access on this web server is currently unavailable. Please hit the "Refresh" button in your web browser to retry your request.
Administrator Note: An error message detailing the cause of this specific request failure can be found in the application event log of the web server. Please review this log entry to discover what caused this error to occur.
Also, when you try to go to http://companyweb/default.aspx
you get the same message