The activation of Poser 5 was disabled as per the latest Service Release (2.1). If that SR 2.1 is not included in your copy of Poser 5, you can download it from CL. If you install Poser 5 without the SR1, you will still have some time (don't remember how long at the moment, but it's a certain amount of days...) until the the activation has to be done. You will have enough time to install the SR1 and forget about the entire activation thing.