I've just solved an issue with my GNU Screen setup on my new Mac for quite a while, and I thought I'd share the solution in case anyone else has this issue.

I use a shell script to initialize a customized screen session when I'm editing a Ruby on Rails application. This script launches a database console, AutoTest session, and development Mongrel instance, and organizes and titles all the screen windows.

I developed it some time ago on a MacBook Pro, and it suddenly stopped working properly on my new Mac Pro. The symptom was that all the shell-based windows worked fine, but the database console, rSpec, and AutoTest sessions all failed to boot, leaving blank screen windows.

The problem turns out to be Leopard's default screen command. It breaks the $PATH variable. The solution quoted in that post is to hard-code a shell command in .screenrc, but my solution was a little different. I just opted for installing the MacPorts version of screen instead. It's more up-to-date, and doesn't clobber the path.

sudo port install screen