I am having this same exact problem. Once a forum is clicked, the permalink updates in the address bar, but the page just reloads itself. It also takes quite a while to load… like its still looking for something. I have deactivated all my plugins and rulled them out. I also tried clearing my cache, and had someone else test on a different machine. Still no luck.
So, after reading this thread, I tried messing with my permalink structure. I changed to default, then reset the slug and permalink in the options and toolbox… and the forum worked.
The reason I am telling you all of my steps is because, I really need the permalink structure to stay the way it is… otherwise I will have tons of broken links. So, I am desparate to get around this… and figure out why my forum won't work with the permalinks set to “day and name”.
Then it dawned on me, I was putting in the forum slug in the admin panel with a forward slash at the end (redneck-revolution-fan-club/jimmie-van-zant-fan-forum/)
So, then I tried it without the ending slash and, VOILA! It works.
I figured I should continue with this support post… because such a simple thing took me HOURS to figure out. Maybe, hopefully, this information will save someone time in the future.
Word from the wise: Do not enter an ending slash when editing the forum slug!
If you're interested… here is the forum, now functioning well.
http://www.jimmievanzantmusic.net/redneck-revolution-fan-club/jimmie-van-zant-fan-forum/