case USB_INSERTED:
                /* inject an event into the button queue so the main thread
                 * will run the USB-UI code and return after the desired
                 * drivers are enabled */
                queue_send(&button_queue, SYS_USB_ATTACHED, NULL);
                usb_state = USB_POWERED;
#ifdef HAVE_USBSTACK
                /* Check any drivers enabled at this point for exclusive storage
                 * access requirements. */
                exclusive_storage_access = usb_core_any_exclusive_storage();

                if(!exclusive_storage_access)
                {
                    usb_attach();
                    break;
                }
#endif /* HAVE_USBSTACK */
                /* Tell all threads that they have to back off the storage.
                   We subtract one for our own thread. */
                num_acks_to_expect = queue_broadcast(SYS_USB_CONNECTED, 0) - 1;
                DEBUGF("USB inserted. Waiting for ack from %d threads...\n",
                       num_acks_to_expect);
                break;