I tried to post this reply, and kept getting a message saying that it looks spam-like, or contains unacceptable elements. What's the problem? "Thanks, higer. This is the other half of the problem with my non-scrolling mouse you resolved for me. When I clicked on your link and tried to install it, I got a message saying that I already have a newer version on my computer. I assume that must be the software for the non-scrolling mouse? In any case, the optical mouse comment said that I had to uninstall the other mouse software before installing the optical mouse software. My problem is, how do I operate/navigate with the 4000 software uninstalled and the optical mouse newer software not yet installed? I had the optical mouse plugged in, then removed the USB transmitter for the non-scrolling mouse. Then nothing worked, so plugged it back in and the non-scrolling mouse worked again OK. I'd like the have the option to put the optical mouse in operation should anything happen to the non-scrolling mouse. Any thoughts about this mess? Thanks." P.S. The above wasn't accepted when I tried to use it in a reply, but was accepted here. What gives?