uh oh sounds like microsoft strikes again. if we cant beat logitech in the mouse department, then we will make it so their products dont work in windows and everyone will buy intellimice (which I personally hate BTW). Sheesh. are you installing mouseware9?
edit: yes i know you mention you are installing the version 9 drivers, but I mean are you installing just the drivers or the whole mouseware9 package? (which if you arent you should since it has lots of functionality and is really awesome). If you are using a USB mouse, have you unplugged then replugged it in? also go to the mouseware control and make sure that your mouse is detected under 'devices' in the mouseware control panel