Reactivation requirement problem

I have had CS6 Creative Suite on my Mac (now running OS X Yosemite) for over two years now, and suddenly, after restarting the computer, when I want to run Acrobat, it gives an error message that "Suite Product Activation Needed" and says I should launch Photoshop.  However, when I launch Photoshop and go back to Acrobat and try to do anything with it, it just shuts down!