I'm starting a new thread (I was in the zimbraAdmin won't listen on port 7071).
So, I wiped my system clean. Installed a fresh copy of CentOS 4.4 running as DomU (Xen). I made sure to install the xen glibc RPMs, so ti should be running right. The system meets the requirements.
I start the zimbra installer. There were some errors about not being able to write files to /tmp, but that was because /tmp only had write access for root. I changed the permissions there and solved that. I go to the zimbraAdmin login panel, and try to login and nothing happens (it freezes). There are a bunch of errors in the logs.
This is the output of the installer: http://pastie.caboo.se/51891