Multisite - Users cannot log in via /wp-admin/

Hi All,

I have a strange issue (one that is only happening on one particular server). I have installed Multisite on one of my domains to allow for local blogging for the community of our town. It is free so I am not using pro sites nor do I have any plugins activated at present.

I have tried twice with a clean install each time and fresh db and am getting the same issue. Basically if a user tries to go to /wp-admin on their sub domain, it redirects them to the main domain wp-admin therefore they cannot log in.

Example: http://jaxon.finedon.co.uk/wp-admin/

Redirects me to: http://finedon.co.uk/wp-login.php

This means users cannot log into their dashboards.

Even if they then login, and click on the "Visit Dashboard" link, it redirects back to main domain and give same message.

There are litterally no plugins active and I am using default twentyeleven theme.

wp-config:

# BEGIN WordPress
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule . index.php [L]
# END WordPress