No input file specified on login pages

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This is a more detailed re-post (sorry)

I've had a working concrete5 installation for a while when I started getting "No input file specified" everywhere. Updating the .htaccess file from (.*) to . resolved this issue apart from on the login page. The login page itself works but the do-login one does not producing the whole "No input file specified" saga.

I have concrete running in a sub directory but the page urls are from root e.g.www.www.example.com/concrete-page-title...

This is the .htaccess file in my root directory relaying concrete requests to the concrete sub-directory.

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_URI} !(\.|/$)
RewriteRule (.*) http://www.example.co.uk/$1/ [R=301,L]
RewriteCond %{HTTP_HOST} ^example.co.uk$
RewriteRule ^/?(.*)$ http://www.example.co.uk/$1 [R=301,L]
# redirect concrete
RewriteCond %{REQUEST_URI} !^/concrete
# permit normal access to wordpress installation
RewriteCond %{REQUEST_URI} !^/news
RewriteRule ^(.*)$ concrete/$1 [L]
</IfModule>


I have pretty urls turned on, here is the .htaccess file in my concrete sub-directory (/concrete).
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME}/index.html !-f
RewriteCond %{REQUEST_FILENAME}/index.php !-f
RewriteRule . index.php [L]
</IfModule>



The login page is accessible but you get the error when visiting the do_login page (it seems to add in /index.php which I think might be a clue).
www.www.www.example.com/index.php/login/do_login......

Sidenote:
cgi.fix_pathinfo=1

And the site is not hosted with GoDaddy

The sites been for a fair while now with no updates, despite my fiddling I have had no success so any suggestions greatly welcome.