Login rediricting in a loop with domain mapping

I have all my settings in Domain Mapping to use the mapped URL. When I go from the network admin to a site, or from site to site, I get brought back to the log in screen of the site I'm trying to access with this URL.

http://www.mapped.com/wp-login.php?redirect_to=http%3A%2F%2Fwww.mapped.com%2Fwp-admin%2F&reauth=1

If I then enter my credentials and log in, it just loops back to the log in screen.