Have you logged into the admin, and updated the default 'Site' to the 'www.domain.com'? Mezzanine associates each page with a 'Site' so you can serve multiple subdomains with the same database and django instance - and the URL is used for this when not in test mode.
(Basically, go to www.domain.com/admin/sites/site/ and make sure that's correct - if not, edit it)
Does that help?
I have done this before to change a test.domain.com to a
live.domain.com, and it seemed to work ok. The other option you
can try is to just set it to domain.com.
There might be someone else with more Mezzanine knowledge than me who can help, but I think this the best place to start checking, especially if the test domain is still working.
Seeya. Danny.