virtualbox.org

There is no conflict between XP SP3 and VB. The problem with BUSY state is that Windows holds the device for itself, it won't release it because something is constantly accessing it. Just like when you try to safely remove a USB drive while you have Explorer open on it, or a file from it. Only way to get around this, is to get VB to install the passthrough driver for it, then unplug it, get a filter for the device and plug it back in, hoping that XP doesn't take it for itself again.

This doesn't work for my problem - libusb and virtualbox apparently hook USB at either the same level or at conflicting levels. This holds true whether Windows is the host and Linux is the guest or if Linux is the host and Windows is the guest.

Dave

Libusb is not a supported, nor default installed package and it's inner works are unknown to me. Assuming from your information here, I have to say that the devs either know about it and don't do anything about it to prevent any issues with the libraries and function they are there for. Another option is that the devs don't know about libusb and therefore never tested it to make it compatible.