Macbook Pro + Arduino Micro = Trouble?

I am getting a lock up sometimes when loading my Arduino Micro. I've got a busy sketch running, and often the load fails unless I reset the Micro. Now and then, when I do this, my keyboard and mouse stop responding - both the built-in keyboard/mouse and a USB keyboard and Bluetooth mouse. Aside from that, the machine still runs and when I press the power button I see the shutdown prompt, but can't select any item and I'm forced to hard power-down the machine.

Macbook Pro, 15", early 2011
OSX 10.7.5
Arduino 1.0.3

Please post code