Summary: How to switch Rhino back to a stand-alone license.
Related installation help: Troubleshooting Rhino 5 Installation
When I installed Rhino, I clicked the option for using the Zoo but I don't know what it is and I can't start Rhino.
To convert a V5 workstation from using the Zoo to using a stand-alone key: http://wiki.mcneel.com/zoo/converttostandalone