No Subsite Admin/Styles with multisite WP 3.7.1 XAMP install

I am hoping to develop and test my first site – a community website – using multisite on my desktop before uploading to my webhost.
This has been a tortuous process, having already failed miserably with a Bitnami Wampstack installation,and now trying the Xampp route. Now, several weeks later, I am still beating my head against a brick wall trying to get the site operational.
The problem is that, whilst I can sucessfully build & access the site and create sub-sites as a Super Admin, I can’t access the Admin pages for the sub-sites. I can edit the site configurations, and access the subsites, but they remain unstyled and their log-ins do not work.

I have trawled the support sites, and the codex, and it seems the issues might lie in one or more of either the wp-config, .htaccess, or Apache httpd.conf files. I have tried many suggestions,but none of them have worked.

My install configuration is: Clean install of WP 3.7.1 in a separate disc partition (K:) into the K:xampp/apps directory with xampp 3.2.1
pre-installed, Apache/mySQL running and all plugins deactivated. No problems with the subdirectory install, theme Twenty Thirteen & pretty permalinks working.

I think that the relevant lines of the key files are:

my wp-config file:

define('WP_ALLOW_MULTISITE', true);
define('DB_NAME', 'bitnami_wordpress');
define('DB_USER', 'bn_wordpress');
define('DB_PASSWORD', '');
define('DB_HOST', 'localhost:3306');
define('DB_CHARSET', 'utf8');
define('DB_COLLATE', '');
$table_prefix  = 'wp_';

.htacces is:

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

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

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

and the httpd.conf file is:

ServerRoot “K:/xampp/apache”
Listen 80
LoadModule rewrite_module modules/mod_rewrite.so
ServerName localhost:80
<Directory />
AllowOverride Options All
Require all granted
</Directory>
DocumentRoot “K:/xampp/htdocs”
<Directory “K:/xampp/htdocs”>
Options Indexes FollowSymLinks Includes ExecCGI
AllowOverride FileInfo Options
Require all granted
</Directory>
Include “K:/xampp/apps/wordpress/conf/httpd-prefix.conf” `
I have installed the Apache RewriteRules plugin and this gives the following for the running site:

Operational mod_rewrite rules:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /wordpress/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /wordpress/index.php [L]
</IfModule>
Rewrite-Related Settings:
 True: using_permalinks, using_mod_rewrite_permalinks, use_trailing_slashes
 False: using_index_permalinks

Permalink_structure: /blog/%year%/%monthnum%/%postname%/

feed_base ->feed; front -> /blog/; root -> ‘’; index-> index.php

I am now totally out of ideas, with no place to go. My personal configuration is: battered, tortured, despairing, etc, etc…..

Does anybody have any suggestions?