Ive looked for a resolution to this issue and there are resolutions for local user accounts.
basically you have to add a user to the vboxusers group in order to give your virtualbox permissions to access the USB drives plugged into your computer.
However, Im logged into a domain (ldap) account through ubuntu here at the office. It does not list this account in the users list.
Has anyone ever ran into this issue before? and if so did you ever find a resolution to the problem?