Thank you for your reply. I forgot to mention I had already done that.
But since your suggested it, I have completely deleted the jbcore folder (again), reload the page to see that it wasn't properly loading jb, and then reuploaded the Pro version of jbcore to /wp-content/plugins/wp-juicebox using my FTP client.

***The odd thing about all this is that I do have access to 'Pro config options' from within Wordpress.***

My guess is that, after mucking about with this for several hours, that the problem must lie within the juicebox_pro_1.4.2.zip file I downloaded at checkout.
I'm hesitant to download again because I saw I only get 5 downloads and wanted to see if you suggest anything else first.

EDIT: I just re-downloaded the file from e-junkie and repeated the whole process. I even disabled the plugin while replacing the jbcore folder, and deleted the contents of wp-content/uploads/juicebox. Same result.

Could you guys email me the correct pro file? I'm pretty confident at this point I'm not getting the right zip from e-junkie...