I'm having the same kinds of problems as the original poster. I took the advice and downloaded the original modules.php and Your Account directory from the distribution and STILL couldn't get the forum admin to automatically load when I logged in as admin on the Nuke side. I DO have a user named admin and an admin named as admin. When I login through admin.php the forum is still looking for a login. If I log out as admin and login through the forum as admin the admin modules don't load.

This might help. When I login as admin through admin.php (and there is no login on the forum) and I try to acces the forum through the forum button in the admin panel, I get the "You are not authorised to administer this board" message. At the bottom of that page is "Powered by phpBB 2.0.3 © 2001 phpBB Group". and the page is generated from "/modules/Forums/admin/index.php". Could it be that the file "index.php" is the wrong file?