I have a Razer Lachesis with Win7 64-Bit and an Asus p7p55d motherboard. For whatever reason, be it mouse, motherboard, or operating system, I cannot scroll down. I've looked through mouse settings in Windows and reinstalled the mouse drivers several times. I just bought a new Lachesis because I figured the scroll wheel was broken, and the new one doesn't work either, so it is not a physical problem. Unfortunately I don't have any other mice to test it with, and I'm out of ideas as to what could fix it.