Пар не будет работать (отсутствующий libGL.so.1)

Я пытаюсь установить Пар на ноутбуке, который мой сын получает для рождества (под управлением Ubuntu 14.04.3 LTS), однако когда я пытаюсь выполнить Пар впервые (через "Паровой" значок на рабочем столе, это создает), Окно терминала появляется, и мне говорят:

Steam needs to install these additional packages: 
    libgl1-mesa-dri:i386, libgl1-mesa-glx:i386, libc6:i386

Ввод пароля делает свою вещь, затем мне говорят:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libgl1-mesa-glx:i386 : Depends: libglapi-mesa:i386 (= 10.1.3-0ubuntu0.5)
 unity-control-center : Depends: libcheese-gtk23 (>= 3.4.0) but it is not going to be installed
                        Depends: libcheese7 (>= 3.0.1) but it is not going to be installed
N: Ignoring file 'steam.list.disable' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'google-chrome.list.disable' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'webupd8team-java-trusty.list.disable' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'steam.list.disable' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'google-chrome.list.disable' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'webupd8team-java-trusty.list.disable' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

Я нажимаю "Enter", и сказан в раскрывающемся диалоговом окне:

You are missing the following 32-bit libraries, and Steam may not run:
libGL.so.1

Я следовал ответу, найденному здесь, однако он не имел никакого эффекта...

Любая справка ценилась бы.