Installing graphics libraries and desktop services componen[FAILED](See the log file /var/log/vboxadd-install-x11.log for more information.

Hi,
Just a quick note here.
I was trying to install my new Guest Additions to my VirtualBox
4.1.14 to 4.1.18 all of a sudden I got the following exception

Installing graphics libraries and desktop services componen[FAILED](See the log file /var/log/vboxadd-install-x11.log for more information.

By all means, do not restart your machine! I did and I could not log in to my CentOS..
so I had to restore my machine to a previou snapshot that worked....
I tried again, and got the same error.
This I searched the internet and I found this forum thread that helped my solve the problem

https://forums.virtualbox.org/viewtopic.php?f=3&t=49334

All I had to do is to remove the VirtualBoxGuestAdditions symlinks.
 The commands to be executed are the following:

> rm /usr/lib64/VBoxGuestAdditions
> rm /usr/share/VBoxGuestAdditions

A big thanks to the guys that found that solution!
Lessons learned: Always remove the VBoxGuestAdditions symlinks prior to installing the new VBox Guest Additions.
Just to be on the safe side..

cheers.