I too have a Mighty Mouse problem that just started today, and I am completely, utterly baffled. All of a sudden, I turn on my Mac Pro with which I have had *zero* problems since I purchased it in February, and am greeted with the Bluetooth Setup Assistant saying that it cannot 'pair' with my mighty mouse. They keyboard works fine, just not the mouse. I replaced the batteries, made sure it's discoverable and that the light blinks, but the mouse still fails to pair. Any ideas? It's driving me crazy.