tonbo,
Definitely go through the MS support channels and report your problem, because they will give you a new mouse. As it says on the box, it has a lifetime warranty. I've done this twice with the Intellimouse Explorer (both had faulty wire connections where the mouse cable enters the mouse...coincidence, or just crappy design/manufacturing?) Needless to say, when my first mouse went out, I was pissed. Went through the MS support channels, posted my problem, and within about a week, MS shipped a new mouse to me, didn't even have to send the broken mouse in.
good luck,
tr