I just noticed today that for some reason when I try to scroll down, it doesn't seem to do anything about 75% of the time, then it will move a little and then do nothing for awhile. Going up it is fine, and the button click is fine too.
This sucks. This mouse isn't even really all that old. It's a MX-510.
BTW, how in the world did we ever get by without scroll wheels? It's amazing how nice that thing is, and you don't even realize how much you use it until it is gone.