Domain mapping - multiple domains and subdomains

Hi gang,

I've got a domain (for example, blog21.com) mapped to a blog within my WPMU install (blog21.my-wpmu-install.com) along with a subdomain of the original domain (new.blog21.com) mapped there.

We've had the subdomain (new.blog21.com) mapped to the WPMU blog for the past several weeks while we were in development. So far, so good.

Now that we're ready to launch, I just changed the A-record of my URL (blog21.com) to map to the WPMU blog too.

Everything works, except that all visitors to blog21.com get redirected to new.blog21.com, which is bad.

Is there a way I can change the order of the redirects, so that blog21.com gets priority? (i.e. Visitors to new.blog21.com get redirected to blog21.com) ?

For reference, inside my domain registrar, I have changed the 3 A-records to point to my WPMU IP Address.
www --> MY.WPMU.IP.ADDRESS
@ (none) --> MY.WPMU.IP.ADDRESS
* (All Others) --> MY.WPMU.IP.ADDRESS

I also added a CNAME for new.blog21.com to point at .blog21.com.

I thought I'd done everything right. Have I missed a step somewhere? Where can I check the "mapping table" within phpMyAdmin? Which table does that get saved in?

Nick