After a couple of hours trying to get a USB device (USB-to-Serial FTDI) working in VirtualBox with OSX host and Ubuntu 12.10 guest and receiving an error message similar to the follow:
usb 6-3: new full speed USB device number 24 using ohci_hcd usb 6-3: device not accepting address 24, error -110 hub 6-0:1.0: unable to enumerate USB device on port 2
It turns out, the issue lies with VirtualBox, when the machine is given more than 1 processor it fails to properly mount any USB device. The only fix I have found to work is to simply reduce the number of processors back to 1. Once it’s returned the USB devices work simply by mounting them the usual way, from the VirtualBox menu > Devices > USB Devices >.
If anyone find a better solution, be sure to comment below.