I could be off base, but I believe you have to add your user name to
the usergroups in ubuntu or some such thing before I could get usb
working. It's been a while so I'm a bit cloudy on that. Once that is
done (and only after if I remember correctly) can you right-click on
"my computer" --> "manage devices", find the usb ports in the list
(they will have little yellow question marks on them) double click on
the ports, and then click on install driver allowing windows to
automatically install the driver. It doesn't matter if you don't
actually have a driver, as virtual box is actually providing the
driver through guest additions. You just need to go through the
process.