Network admin loop on Multisite


I recently updated my Multisite to 3.5.1 and since then I can no onger access my network dashboard as I get an infinite loop :slight_frown: I've checked and tried everything I can re:htaccess and wp-config, I have no www's anywhere in those or my database so I'm a bit stuck! My htaccess looks like this:

RewriteEngine On
RewriteBase /

#uploaded files
RewriteRule ^(.*/)?files/$ index.php [L]
RewriteCond %{REQUEST_URI} !.*wp-content/plugins.*
RewriteRule ^(.*/)?files/(.*) wp-content/blogs.php?file=$2 [L]

# add a trailing slash to /wp-admin
RewriteCond %{REQUEST_URI} ^.*/wp-admin$
RewriteRule ^(.+)$ $1/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule . - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-.*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

<IfModule mod_security.c>
<Files async-upload.php>
SecFilterEngine Off
SecFilterScanPOST Off

and my wp-config:

/** The Database Collate type. Don't change this if in doubt. */

define('DB_COLLATE', '');

define('VHOST', 'yes');

$base = '/';

define('DOMAIN_CURRENT_SITE', '' );

define('PATH_CURRENT_SITE', '/' );

define('SITE_ID_CURRENT_SITE', 1);

define('BLOGID_CURRENT_SITE', '1' );

define('WP_MEMORY_LIMIT', '500M');

Happy to supply logins if it helps?

Thankyou already!