Steam includes libx11, but it's only used by steam and not installed via the package manager. Ubuntu recently released an update to the X stack which broke systems in the way you describe, maybe that affected you? We have a workaround for steam, but wine was also affected and I don't believe they have a workaround at the moment.
I would recommend uninstalling your 32-bit packages if you don't need them, running sudo apt-get install -f, and then installing steam fresh from the website:
http://store.steampowered.com/about/
Nothing extracted yet.
I really don't know what happened.
I have kubuntu 13.04 64bit system. And it has been working pretty well. I haven't seen any serious issues. I am updating it with trusted sites.
I had wine and Playonlinux, because not all my games are still playable via steam.
Well I got some update via the "channel", it had libx11 (or something like that) after the update it had deleted my playonlinux, wine and the system got screwed.
I browsed another thread here and I noticed that that libx11 file is in steam package.
So I am quessing here that system updated the file and it was no longer compatible with the version steam was using?
I made a report on ubuntu about this situation, but at the I wasn't aware that steam uses the fie.
I had to reinstall some files to get kde working again.
When I tried to run steam it complains that not all my files are there and it tries to update, but not able to update them all.
steam
QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.
Fontconfig warning: "/etc/fonts/conf.d/50-user.conf", line 9: reading configurations from ~/.fonts.conf is deprecated.
opens another terminal window with message:
team needs to install these additional packages:
libgl1-mesa-glx:i386
[sudo] password for jarkko:
.......................................................................................................................................W: Failed to fetch http://ppa.launchpad.net/lucid-bleed/ppa/ubuntu/dists/raring/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/lucid-bleed/ppa/ubuntu/dists/raring/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/lucid-bleed/ppa/ubuntu/dists/raring/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
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: libx11-6:i386 (>= 2:1.4.99.1) but it is not going to be installed
Depends: libx11-xcb1:i386 but it is not going to be installed
Depends: libxdamage1:i386 (>= 1:1.1) but it is not going to be installed
Depends: libxext6:i386 but it is not going to be installed
Depends: libxfixes3:i386 but it is not going to be installed
Depends: libxxf86vm1:i386 but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
Press return to continue: