After you download it, it nags you to buy the premium version. Well after buying it you find that the free version that would not let you use the settings was for real. The full paid version will not let you use the settings either. You can email tech support and customer relations at RI Soft Systems, and they will not answer you, but they will run your credit card surely. I got my Living Marine Aquarium V3 from Ri Soft Systems. They are affiliated with Freeze.com.I tried to use it on a new computer with Windows XP. There should not have been any problems.