Perfect, thanks. I'll have a look at those settings.
Re reproducing the error, if you access employee portal, allow your inactivity timer to expire, then at the "Disconnection Problem" message reply "no" (as you might do if you had entered a lot of info) then you will get the error if you try to navigate to a Service Domain page. If navigating to the Home page you get a slightly different message "The 'Home Page' has not been created yet".
Workaround is to refresh/authenticate and all is well.
Thanks for your responses Daniel. I think we understand now, and can advise our folks accordingly.