403 Forbidden problem when changing / edit options
 

Vbulletin,

I have a small problem with permissions. I was wondering if it's apache from my host or vbulletin. Can i fix it with a line of code or something else.

Problem
In admincp when i go to forum manager to change and update a forum.
Also when users try to make a new thread they get the same message for /newthread.php

Error
403 Forbidden

You don't have permission to access /admincp/forum.php on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
Apache/2.2.15 (Unix) mod_ssl/2.2.15 OpenSSL/0.9.8n DAV/2 mod_fcgid/2.3.5 mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 Server at www.yourforum.com Port 80
This 403 is almost on everything i edit or want to change.

When did the problem occur?
After updating from 3.7.4 to 3.8.4 and installing a new style.