How to stop Non-WWW Wordpress MU getting redirected to signup/register page?

So we have Worpress MU install and removed the WWW in the URL, as mentioned here http://codex.wordpress.org/Create_A_Network

Why is it that when we go to

http://internetmarketingpages.com - it loads correctly
but when we use
http://www.internetmarketingpages.com
it redirects to
http://internetmarketingpages.com/register/

We are aware that the /register/ page is set by Buddypress as we are using it as well.

Since we originally had a www on the site, our browsers now change the url to http://www.internetmarketingpages.com if we enter in internetmarketingpages.com.

How do we stop the redirection from happening even if we enter in the URL with WWW?

Please advise.