What does your root look like, give me a picture of where your forum is in the root.
it would be at root/hidden
Is there a physical index.php in that location? All write/read permission set correctly and the install went ok? i.e did you set forum URL as it asked in the install.
I didn't set a forum URL, I did set a main site URL, And yeah, install was OK, there's an index.php at the location, and the permissions are fine. I'll check the URL in config real quick.
Edit: URL is also fine.
Nah, no plug-ins installed at all.
Edit: re-install fixed the problem.