For some reason, when using docker machine on a mac, the VM always fails to start and freezes at the "VM starting" phase. For this reason, I've had to switch back to boot2docker.
Super sorry to hear - we've had some issues with VirtualBox around networking and some setups we didn't anticipate -- Would be really appreciative if you'd give the latest 0.3.0 release candidate a whirl and see if it fixes the issue for you: https://github.com/docker/machine/releases.