VirtualBox Failed to access the USB subsyste

If you receive the error message in VirtualBox Failed to access the USB subsystem, follow the guide below.



Ensure that the you have installed the latest VirtualBox Extension Pack. These are available from the downloads page on the VirtualBox website.
Ensure that the Extension Pack version you are downloading matches the version of VirtualBox that is installed on your machine.

In this example below VirtualBox 4.1.18 is already installed, so you need to download the VirtualBox Extension Pack 4.1.18



Once you have downloaded the VirtualBox Extension pack, either double click to install, or whilst VirtualBox is open drag and drop the package inside the left hand pane. A confirmation box will appear asking to you install it.



Once installed, under settings make sure that the Enable USB controller and Enable USB 2.0 (ECHI) Controller options are both checked.



Next, open your terminal and enter the following command below.
The command below adds you to the vboxusers group and will fix the error message.

Make sure to change {Username} to your current username without the parenthesis

Finally you need to Log out of Ubuntu and then log back in. You will then be able to access your USB devices in your Virtual machine.

from: http://www.techheadz.co.uk/259.html