After using this mouse very lightly and gently for 2 months, the left mouse button stopped working about half of the time. I called Microsoft Customer Support this morning and they said that could not help me. So, now I'm stuck with a $40 mouse that doesn't work.Don't get me wrong, this is the most comfortable mouse I've ever used. But, when all is said and done, it cost me about $0.75 per day of use, which is much too expensive for any mouse.