are you aware that you've posted this question in at least three different places? since nobody's responding i'm going to report that either they don't want to answer, they don't know the answer, they're annoyed by the fact that you're posting multiple times, or they think it's common sense to know that if your mouse isn't working correctly then you should check your mouse drivers... update them, reinstall them, etc. if that doesn't work, then close maya, delete your prefs folder from your maya directory, and re-open it. if it's still not working, get a new mouse... they're like 10 bucks.
Accept no substitutions.