<< If your MS optical mouse ever breaks or starts malfunctioning, just call this number and press "0" to talk an operator. They will ask you for a # on the bottom of your mouse, take your mailing info and then send you a new one. They do not ask you to send your old one back. My right mouse button broke a couple weeks ago and I called. Worked great. Got my new mouse in about 5 days.
The # is: 1-800-360-7561
Then select "0" >>
Yup, this lifetime warranty is sweet. I have 1 dead one, 1 that just doesn't work with UT, and 1 that's all good... all for the price of 1.