weird www redirect problem

Ok, so this is weird. When i put in http://www.tasartslive.com/pagename it redirects back to tasartslive.com - if i put it in with no www. it takes you to the correct page. Im pretty sure this is something to do with canonical URLs but im not sure where id go to suss out the problem.

In my wp-config its defined like this:

define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', false );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'tasartslive.com' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );
define('WP_MEMORY_LIMIT', '128M');

should i add the www. to the DOMAIN_CURRENT_SITE? If i do that, will it work without a www. aswell?

Any help appreciated

Thanks!