Yes, SuperSparks, the new mouse (also optical cordless) worked fine. However I'm returning the new "desktop duo"; the mouse was smaller and uncomfortable under my hand, and the keyboard lacked some features I liked. Igbpop, you may have the ticket, and thank you for the enlightenment regarding "contact" where optical mouses are concerned. The new mouse seemed very sensitive and slid too easily on my bare desk surface so I put it on ..... a piece of paper. After I uninstalled and returned to the old mouse, the paper remained and I found that the old mouse was working much better. I wondered why (was it the mouse's fear of being deported? ) It's still malfunctioning sporadically, but, useable. Thanks again for your help. I'm still going to contact the manufacturer, and will let you know what ensues.
Chas