Installer thinks my product is counterfeit but it's not!!!

I was having trouble opening photoshop CS6 so I uninstalled it and now I'm reinstalling to see if that resolves the problem. The installer is telling me my product is counterfeit, but I bought this software about three years ago. I'm re-installing photoshop on a new computer and I have it on my old computer. How can I bypass the genuine software verification failure? Why doe it think my product is fake?