virtualbox.org

The dkms in my Linux Mint guest was up to date.
Then I attempted to install the Guest Additions:

In Terminal, root & Guest Additions wrote:Iris VBOXADDITIONS_4.2.10_84104 # sh ./VBoxLinuxAdditions.run
Verifying archive integrity... All good.
Uncompressing VirtualBox 4.2.10 Guest Additions for Linux..........
VirtualBox Guest Additions installer
You appear to have a version of the VBoxGuestAdditions software
on your system which was installed from a different source or using a
different type of installer. If you installed it from a package from your
Linux distribution or if it is a default part of the system then we strongly
recommend that you cancel this installation and remove it properly before
installing this version. If this is simply an older or a damaged
installation you may safely proceed.

Do you wish to continue anyway? [yes or no]
no

Cancelling installation.
Iris VBOXADDITIONS_4.2.10_84104 #

What do I need to remove? How do I remove it? (I read the 'User Guide' sections on this and didn't understand because I'm a Linux newbie.)

Thanks for your help - Mark.

Mint comes with a pre-install version of the guest additions and it is not the ones from VirtualBox. If you try to install over it the guest will not work properly.

There are two ways to remove them, the terminal and the package manager. If you use the package manager you must be sure to remove all the packages (mint has several). I find the terminal to be the easiest and use the following command:

Thanks, Perry!

Could you suggest to the developers they do that as a first step in the installer?

Ciao - Mark.

They already do check (indicated in your first post on this topic). I doubt they are going to expend the necessary resources to try and figure out all of the different versions and what not to remove them automatically, but you are more than welcome to post an enhancement on bugtracker.