I allow unregistered / unlogged in users to access "Active Topics". They can mouse over and see the excerpt just fine.
But, if they click on the link to the (spider-friendly) thread (any and all threads) they get:
FATAL_NO_FILE scripts/show.inc.php
Please use your back button to return to the previous page.
I don't have a show.inc.php in /scripts on my server. I won't be able to check if it was in the zip file until tomorrow. It is possible I missed it.
Thanks!