I have vbox 4.1.14 and the same problem with the usb and i solved doing this.
First make a copy of this file: cp -a /etc/init.d/mountdevsubfs.sh /home/user
then open de file
sudo gedit /etc/init.d/mountdevsubfs.sh
and add the following lines at the end:
# Virtualbox - for use the USB
mkdir -p /dev/bus/usb/.usbfs
domount usbfs "" /dev/bus/usb/.usbfs -obusmode=0700,devmode=0600,listmode=0644
ln -s .usbfs/devices /dev/bus/usb/devices
mount -rbind /dev/bus/usb /proc/bus/usb
and save
Now you have to create two new files
sudo gedit /etc/udev/rules.d/40-permissions.rules
and add the following lines:
LABEL="usb_serial_start"
ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", \
,GROUP="vboxusers", MODE="0660", GROUP="dialout"
LABEL="usb_serial_end"
save and quit
the other file...
sudo gedit /etc/udev/rules.d/40-basic-permissions.rules
and add the following lines:
# USB devices (usbfs replacement)
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", MODE="0666"
SUBSYSTEM=="usb_device", MODE="0666"
save and quit
reboot your system
hope this work to you, it helped to me
sorry for my english