error 400 when hiding index.php

[eluser]gRoberts[/eluser]
Hey everyone,

I have a site set up like the following:

Code:

htdocs
    \a
        \.htaccess
        \index.php
        \uploads
    \b
        \.htaccess
        \index.php
        \uploads
    \index.html
sites
    \a
    \b
system

With index.php enabled and .htaccess renamed/removed, it works fine. But with the index.php within the URL.

When I remove the index.php from the config and enable the .htaccess, it throws an error 400.

my .htaccess file:

Code:

RewriteEngine on
RewriteCond $1 !^(index\.php|assets|robots\.txt|uploads)
RewriteRule ^(.*)$ index.php?/$1 [L]

Anyone got any idea's as to why?

Cheers