Multi-Site Error: Warning: An existing WordPress network was detected.

Hi there,
I’m trying to set up a multi-site install. I’ve done this successfully a few times before. All plug-ins were deactivated before I begin. This is being done on a pre-existing site with lots of content on the db, so I can’t just nuke the db’s and start over.
Here are the exact steps I’ve taken:

Multi-Site install:
1) go into wp-config.php and put
define('WP_ALLOW_MULTISITE', true);
right before the line
/* That’s all, stop editing! Happy blogging. */
2)Refresh browser and clear cache
3)Login to wp dashboard. Go to tools > network
Error:

Warning: An existing WordPress network was detected.

Please complete the configuration steps. To create a new network, you will need to empty or remove the network database tables.

Some posts I found said to try just forging ahead, which worked for some people.

4)Create a blogs.dir directory at /home/fundoc/public_html/wp-content/blogs.dir. This directory is used to store uploaded media for your additional sites and must be writeable by the web server.

5)Insert code into wp-config.php just prior to last line:

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

6)Back to dashboard, refresh ‘network’ page. It boots me out into login page. When I try to login, it just keeps looping through asking me to login, never actually logging me in.
7) Website is still up and accessible however, just can’t get into dashboard.
8) Go ahead and add code to .htaccess file (which was empty) to give it multi-site rules

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).*) $1 [L]
RewriteRule  ^[_0-9a-zA-Z-]+/(.*\.php)$ $1 [L]
RewriteRule . index.php [L]

9) Still can’t login to dashboard, but site works

10) I undid the above steps, and could login fine, but of course no multi-site. Ability to login seems to break as soon as I do step 5.

11) Tried it all again with the same results.

Thanks for any suggestions anyone may have.
Mieren