Eu tive o mesmo problema, que resolvi seguindo as instruções do link :
This is a problem with steam and ubuntu 15.04. Steam bundles old libs and are colliding with mesa drivers, that is also why closed drivers aren't seeing this problem.
There is a open bug in steam github the workaround for now is to remove the old lib version, at least until valve fix the issue in their startup script or similar. So enter this folders and do this
Code:
cd $HOME/.steam/ubuntu12_32/steam-runtime/i386/usr/lib/i386-linux-gnu mv libstdc++.so.6 libstdc++.so.6.bak cd $HOME/.steam/ubuntu12_32/steam-runtime/amd64/usr/lib/x86_64-linux-gnu mv libstdc++.so.6 libstdc++.so.6.bak
It worked for me... but please note that if some game required that old lib from the steam runtime, it may crash (that is why should be valve fixing this)
Editar: As etapas do segmento já foram citadas de problema com a instalação Steam no Ubuntu 15.04+ , assim você pode ir lá para mais detalhes caso essas instruções não sejam suficientes para você resolver o seu problema.