I\'ve set up a MU install with two domains, using the WordPress MU Domain Mapping-plugin.
The system is first configured with subdomain d2.domain1.com (under sitesan
This is another solution
define('ADMIN_COOKIE_PATH', '/'); define('COOKIE_DOMAIN', ''); define('COOKIEPATH', ''); define('SITECOOKIEPATH', '');
to wp-config.php file.