Ok, so I removed all trace (incl settings!) of Stardock products and started again.
ObjectDesktop dies very fast, same fault as before - gets as far as drawing this window:

Fences 4 - individual install, went flawlessly. Works fine.
It appears I can use individual programs, just not the Object Desktop manager. I have no extra information in that regard. Perhaps if someone can make an older release available to me to try?