Suddenly, when I click on any of the Nik Collection plugins, I get error messages. If I have an image open in Photoshop and click to open Color Efex Pro 4, I get the message attached below. Similarly, if I attempt to open Viveza 2, I get the message "The command 'Viveza 2' is not currently available."
I'm working in Photoshop CS6 13.0.6 and have changed nothing in my preferences or computer setup that would account for this.
What does this mean, and how do I fix it?