If you receive this error message while running VirtualBox under Ubuntu/Debian:
Failed to access the USB subsystem.
Could not load the Host USB Proxy Service
(VERR_FILE_NOT_FOUND). The service might not be
installed on the host computer...
Then follow these instructions:
1. Open the Terminal and edit this file as follows under Ubuntu:
sudo gedit /etc/fstab
2. For Debian, edit it as follows:
3. And add this line at the end of the file:
usbfs /proc/bus/usb usbfs defaults,devmode=666 0 0
4. Save the file and close it.