Can't login after network subdomain install with 3.1

Hi, I’m running WP 3.1 on Ubuntu 10.10, running apache 2.2 and php 5.3.3. I’m using dnsmasq for my local dns and I was hoping but [slowly losing that hope] to build a subdomain network install of wordpress.

Logging in after making the alterations below fails/loops me back round to the login screen

I’ve spent 4 days researching and trying to get the thing working so this is really the last port of call for me. I’m hoping I’ve just missed one small thing!

My dnsmasq.conf has these two sections in it.
address=/.davidt/127.0.0.1
for handling wildcarded subdomains, and
listen-address=127.0.0.1
I’m on a local development machine, and this seems to be working ok. WP stopped throwing its ‘tried to access random subdomain’ error once this was in and running, and in conjunction with some virtual host config, is serving virtual hosts from the one IP and DNS cacheing as a bonus ; }.

The relevant bit of apache onfig look like this
ServerAlias *.davidt
and apache is starting without error and apachectl -S shows the other virtual domains loading happily and the syntax for this part of the config error free.
Syntax OK
and

david@david-ThinkPad-Z61t:/var/www/dyson$ sudo /etc/init.d/apache2 restart
* Restarting web server apache2
... waiting .
[ OK ]

Copied the WordPress generated code into the right places thus – wp-config.php

define('WP_ALLOW_MULTISITE', true); ¬                                      

define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', true );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'davidt' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );|~                                                                            

/* That's all, stop editing! Happy blogging. */

and built an .htaccess file – none there at the start – using the generated code thus…

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

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule . index.php [L]

Site runs but admin doesn’t, and commenting out of the new code in wp-config.php returns to be a single instance install of wp’s admin console.

Any ideas would be most gratefully received – I’ve tried everything I could find to date.

Rgds, and in the hope I can help you out one day soon…

bdjt