Gemini is designed to work with 5.0 or better (when released OFFICIALLY). It won't accept a lower OS because they will not be designed for that device. Any lower OS's "floating around" are not considered "available". The tosser that gives you one is probably violating some agreements with RIM as a beta tester. When RIM notices this he'll get his status as a beta tester yanked and have the OP to thank.