If you have never installed OptiSystem 13 before on your PC and you are facing this problem, you can contact Optiwave technical support at support@optiwave.com for your problem. This error is supposed to happen when optiSystem has formerly been installed on a PC and 30 days have passed.
You’re welcome Mohamed. It has happened to me before when I had installed the software and then changed my system time. I had to wait for a day and then the problem was over without any further action being taken by me! However, reinstalling seems to be a much better solution.