My cousins computer wasn't working so i took out the HardDrive and put it in my computer. Then I installed Windows 2000 Professional on it. I went back to their house today to put the HardDrive back in and it won't work, the computer will not boot Windows 2000. I checked the cables to make sure everything was in the right place, it was. Does anybody know whats wrong? What can I do to fix it?