OK, next question. Is it an ATX motherboard or is it a motherboard that has a cable from the ps2 port to the Motherboard? If it is an atx motherboard were there special drivers that came with it? if not I would have to assume the mouse is bad... take it back to (Came apart) If it has a cable make sure the cable is installed correctly and if so take the connector off and put it on a couple of times. There may be some corrosion on the pins which keep it from working correctly. Larry Visit our website regularly for FAQs, articles, how-to's, tech tips and much more http://freepctech.com