title: Could not mount the media/drive '/usr/share/virtualbox/VBoxGuestAdditions.iso' (VERR_PDM_MEDIA_LOCKED)
body: <p>I'm trying to install latest VBoxGuestAddtions.iso (<a href="http://download.virtualbox.org/virtualbox/" rel="nofollow noreferrer">link</a>) in Ubuntu system. When I mount ISO image as CD-ROM I see this error:</p>
  <p><strong>Could not mount the media/drive '/usr/share/virtualbox/VBoxGuestAdditions.iso' (VERR_PDM_MEDIA_LOCKED).</strong></p>