I could have swore I put the instructions to edit that in the install file, but I guess not. Sorry about that...
You can fix it by editing your head_newpm template and looking for 2 places that you'll see private.php. Just add /fourms/ (or whatever your forum folder is called) in front of that and it should fix the problem.
By the way, I haven't forgotten about your PM. I've just been really busy this week and haven't had a chance to look into those problems you asked me about yet. I'll try to look at those for you before the weekend though.