WordPress site is showing 404 error for pages – but with my IPB forum

I have a WordPress website, running at the root of my website. And an invision install running on the directory /forums/

I’m using a code to show a welcome $USER$ if logged into IPB, now recently without any change to my knowledge, possibly an update to IPB, every WordPress page/post kicks out a 404 error. But not a 404 in WordPress, a 404 under the forums?

You can see this here:

http://www.tfuhq.com/ – WordPress home page (WORKS)

http://www.tfuhq.com/autobots/ – WordPress internal page (404)

http://www.tfuhq.com/forums/ – FORUMS (WORKS)

This is the htaccess for the wordpress install:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

This is htaccess for the forums:

<IfModule mod_rewrite.c>
Options -MultiViews
RewriteEngine On
RewriteBase /forums/
RewriteCond %{REQUEST_FILENAME} .*.(jpeg|jpg|gif|png)$
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule . /forums/public/404.php [L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /forums/index.php [L]
</IfModule>