I decided to try my custom dotnetnuke shopping cart module on a different version of DNN to see how it fared - a common practice among dotnetnuke module developers. I installed a new DNN instance and then used a template to set everything up. The version test went great, but the second I tried to add a new text module to the home page, the installation became corrupted and I couldn't recover it. After retracing my steps, I figured out that the cause was a some difference in the portal export feature. Lesson learned - only use create new portals from templates made in the same version of DNN.