Debian/Shorewall routing issues (from Shepherding Computers)

I've recently deployed a new router running Debian Squeeze and Shorewall. The problem started like this:

I have my network configured with five vlans for different areas (servers, workstations, sandboxing, guests, and DMZ) and a /28 subnet assigned for each zone all the fancy network math done.

Everything worked fine until I had to get machines to talk to the outside world.

Shorewall has configurations for 5 zones (corresponding neatly to the vlans) and a few filtering rules for each one. One ... Cars Bicycle Horse