I had an MS Intellimouse Explorer. After a year I found out Microsoft said it was defective, however they refused to replace it for me. So I decided, ok I'll go out and buy a new one, seeing as how I liked the mouse. Well 6 months later, I noticed that it too was having problems. It would freeze up my PC, it would "turn off" (the light would go off). Both of these problems MS recognized however again, they said they would not give me a new one. A few months later I noticed that when I would single click, the mous would recognize this as double click, or even more. Using a little click counter program I wrote, I noticed that at one point, clicking the mouse once resulted in 6 clicks. At that point I said bye-bye to MS and said hello to Logitech. Ok yea the MX700 cost a bit more ($80), but I've had it for about 5 months now and I haven't had a single problem.