htaccess issues with initial setup

I’ve just set up a multi-site for my first time.

I followed all steps within the WordPress documentations, but once I created the .htaccess file and uploaded it to the main directory, I would get an error 500 on all WordPress sites.

I then grabbed the htaccess code from here http://perishablepress.com/htaccess-code-for-wordpress-multisite/ and now WordPress loads and multi-site is set up. Unfortunately, now the url’s are messed up. My url’s now look like:

http://domain.comdomain.com/wp-admin/network/sites.php

Any idea why this is happening?

/* Multisite */
define( 'WP_ALLOW_MULTISITE', true );
define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', false );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'domain.com' );
define( 'PATH_CURRENT_SITE', 'domain.com/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );
/* That's all, stop editing! Happy blogging. */

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

# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [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]