No login possible after creating multisite?

Hi everyone!

I’m trying to install a WP multisite on my (German) 1&1-server and run into all sort of trouble as soon as I change the .htaccess and the wp-config.php ??

I tried to choose subdirectory addresses (though it would be easier not touching the DNS thingie) and learned the hard way that it’s just possible with a fresh, clean install without already imported articles. Okay, so I started with a fresh, clean install (as mfields described here). To make permalinks work on 1&1 I needed to change .htaccess to:

AddType x-mapp-php5 .php
AddHandler x-mapp-php5 .php
Options -MultiViews

After that I followed the multisite setup instructions, chose the subdirectories scheme, and copied the following into my .htaccess:

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]

Into wp-config.php I copied

define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', false );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'mydomain.de' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );

and kept the

define('WP_ALLOW_MULTISITE', true);

part,too. Or do I have to remove that?

Anyways: As soon as I log out and try to log in into the backend again, the system won’t accept my password (or any new passwords that WP generates for me). I walked through the process numerous time – to no avail.

I’d greatly appreciate any ideas how to solve this – thanks in advance, Gabi