For all of you who use VirtualBox on OS X with host-only interfaces: VirtualBox on Mavericks will prevent the OS from shutting down if you have host-only interfaces configured (and will clutter your dock with VirtualBox icons…). You may use the attached bash script to fix the symptoms (there’s no solution yet). You will need to edit the script to match the number of host-only interfaces you have configured. Cheers, Max