My wireless Microsoft Intellmouse Explorer 2.0 became a slug. It was non-responsive and very slow. Changing the battery did not help. I had version 5.0 of the Microsoft Mouse.app in my applications folder. > The current version of the Intellipoint software is 6.0, and is > available from the Microsoft web site: > > http://www.microsoft.com/hardware/downloads/default.mspx > I downloaded and installed the v 6.0 software and the mouse started working perfect. If you MS mouse is non-responsive, I suggest you get the new software.