Yes. I've completely uninstalled it from the second machine and reinstalled it while the other wasn't running and it still gives the same error message.

Coincidentally I'm switching broadband provider today so will uninstall Zorro from both devices and hunt for any associated files and get rid of them too. Then once the provider has switched I'll download Zorro to the second machine first and hope this solves it.

Will update with my results when I'm done.