Fix redirect loop on Wordpress MU site.

I've installed Wordpress 3.0 on my VPS. I've enabled the 'multisite' feature and I'm trying to map each child site to its own domain. I'm using this plugin: [login to view URL] The problem is when I map a new domain, it will get stuck in a redirect loop. My server is running Apache and Ubuntu 10.04, I've added the DNS entried for each domain I want on the server. I need to be able to add new domains without them getting stuck in redirect loops. This should be very simple for anyone who is knowledgeable about Apache.