I've tried installing/uninstalling with no change in effect.

System requirements include "MacBook 5,1 (or later)", I'm running a MacBook 8,1.

I'm not running Little Snitch.

I've not yet tried running under a new user (I will attempt shortly)

What's the Autodesk address that I can't connect to?  I'll try pinging it.

Since I've already received my S/N and Key, I entered that information during installation.  It's possible that NOT entering that information during the installation, and subsequent "manual registration" may make the difference.