Building the main Guest Additions module ...done.
Building the shared folder support module ...fail!
(Look at /var/log/vboxadd-install.log to find out what went wrong)
Doing non-kernel setup of the Guest Additions ...done.
Installing the Window System drivers
Warning: unknown version of the X Window System installed.  Not installing
X Window System drivers.
 ...done.
Installing graphics libraries and desktop services components ...done.
alistair@alistair-VirtualBox:/media/alistair/VBOXADDITIONS_4.3.12_93733$