Re: config seems to be inserting an extra /forum/ in the path…
Actually, you have your name being /forum/ and then when it goes to the forum, it is ironically named forum as well. Hense, the:
If your forum was called discussions it would come up as:
Problem for the 404 error seems to me to be because something is wrong with your fancy permalinks. I would check out the following link and make sure everything is according to the docs:
If you still can’t get it working, then maybe turn off the permalinks in the config.php file to make sure it is the permalinks that are causing the problem.