Ask a mod to close this thread and create a new one in code modifications because there you will get people who are experienced PHP coders etc and they would be able to help you better than us because in this section we only help people with general support.
Is this custom php file generating any templates? Can you post the code of the custom index.php so we can see it?
I just renamed index.php to forum.php on one of my localhost installs on MyBB (I have three, one Alpha of 1.8, one for plugins on a default theme, and one for a theme I'm working on in my spare time), and it worked.
So try renaming index.php to forums.php and install your custom index.php to your existing forum.
Only one code edit I saw that needed it, open up global.php, find (around line 591):
$navbits[0]['url'] = $mybb->settings['bburl']."/index.php";
Replace with:
$navbits[0]['url'] = $mybb->settings['bburl']."/forums.php";
There may be other edits needed, but they should be easy to find and fix.
Yea, I did that too Seabody, probably following the same threads etc as you did.
Thanks guys for the help, moving mybb forum into another folder can save me from having to edit files like index.php and just redirect everything from inside the root with .htacess. Also if I decide to use the SEO urls plugin I probably would be better off now to set it outside the root rather then down the road where then it might get tricky or i might even be more stuck in the middle of a huge update or what not.