Well, I have a Mac Air, and i recently partition windows on it. but now when i log in says "The Windows Vista Home Premium product key you typed is invalid for activation". and the choices they give you are : 1. access your computer with reduced functionality 2. type a different product key 3 contact microsoft to help resolve this problem. you see, i also got a new destop, and it came with a windows CD, so i figured maybe i can use it to partition windows on my mac. it did work for a few weeks, but now this happens. so what do i do now? i dont know where the product key is located and i dont want to buy a windows installation disc for its product key. i just want to go back to mac? but how? help.