Verifying archive integrity... All good. Uncompressing VirtualBox 4.3.28 Guest Additions for Linux............ VirtualBox Guest Additions installer Removing installed version 4.3.28 of VirtualBox Guest Additions... Copying additional installer modules ... add_symlink: link file /usr/lib/x86_64-linux-gnu/VBoxGuestAdditions already exists add_symlink: link file /usr/lib/VBoxGuestAdditions already exists add_symlink: link file /usr/share/VBoxGuestAdditions already exists Installing additional modules ... Removing existing VirtualBox non-DKMS kernel modules ...done. Building the VirtualBox Guest Additions kernel modules The headers for the current running kernel were not found. If the following module compilation fails then this could be the reason. Building the main Guest Additions module ...done. Building the shared folder support module ...done. Building the OpenGL support module ...done. Doing non-kernel setup of the Guest Additions ...done. You should restart your guest to make sure the new modules are actually used 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 ...fail! (See the log file /var/log/vboxadd-install-x11.log for more information.) Press Return to close this window...