https://github.com/ValveSoftware/steam-for-linux/issues/2740
You probably have some missing dependencies.
┌─[solomon@Sucker] - [~] - [2013-07-28 04:13:17]
└─[0] ldd .local/share/Steam/ubuntu12_64/steamclient.so
linux-vdso.so.1 (0x00007fffb79fe000)
libtier0_s.so => not found
libvstdlib_s.so => not found
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fad6abc1000)
libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007fad6a883000)
libusb-1.0.so.0 => /lib/x86_64-linux-gnu/libusb-1.0.so.0 (0x00007fad6a66c000)
libopenal.so.1 => /usr/lib/x86_64-linux-gnu/libopenal.so.1 (0x00007fad6a411000)
libpulse.so.0 => /usr/lib/x86_64-linux-gnu/libpulse.so.0 (0x00007fad6a1c6000)
libgobject-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 (0x00007fad69f76000)
libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007fad69c76000)
libdbus-glib-1.so.2 => /usr/lib/x86_64-linux-gnu/libdbus-glib-1.so.2 (0x00007fad69a4f000)
libnm-glib.so.4 => /usr/lib/libnm-glib.so.4 (0x00007fad69811000)
libnm-util.so.2 => /usr/lib/libnm-util.so.2 (0x00007fad695ae000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fad692b0000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fad690ac000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fad68da8000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fad68b8c000)
/lib64/ld-linux-x86-64.so.2 (0x00007fad6c029000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fad687e0000)
libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007fad685c0000)
libudev.so.0 => /lib/x86_64-linux-gnu/libudev.so.0 (0x00007fad683b1000)
libjson-c.so.2 => /lib/x86_64-linux-gnu/libjson-c.so.2 (0x00007fad681a5000)
libpulsecommon-4.0.so => /usr/lib/x86_64-linux-gnu/pulseaudio/libpulsecommon-4.0.so (0x00007fad67f37000)
libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007fad67cf2000)
libcap.so.2 => /lib/x86_64-linux-gnu/libcap.so.2 (0x00007fad67aed000)
libffi.so.6 => /usr/lib/x86_64-linux-gnu/libffi.so.6 (0x00007fad678e5000)
libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007fad676a7000)
libgio-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0 (0x00007fad6734b000)
libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007fad67345000)
libgcrypt.so.11 => /lib/x86_64-linux-gnu/libgcrypt.so.11 (0x00007fad670c6000)
libgnutls.so.26 => /usr/lib/x86_64-linux-gnu/libgnutls.so.26 (0x00007fad66e06000)
libgmodule-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgmodule-2.0.so.0 (0x00007fad66c02000)
libgudev-1.0.so.0 => /usr/lib/x86_64-linux-gnu/libgudev-1.0.so.0 (0x00007fad669f8000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fad667e1000)
libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007fad665dd000)
libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007fad663d7000)
libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007fad661d5000)
libICE.so.6 => /usr/lib/x86_64-linux-gnu/libICE.so.6 (0x00007fad65fba000)
libSM.so.6 => /usr/lib/x86_64-linux-gnu/libSM.so.6 (0x00007fad65db2000)
libXtst.so.6 => /usr/lib/x86_64-linux-gnu/libXtst.so.6 (0x00007fad65bad000)
libwrap.so.0 => /lib/x86_64-linux-gnu/libwrap.so.0 (0x00007fad659a2000)
libsndfile.so.1 => /usr/lib/x86_64-linux-gnu/libsndfile.so.1 (0x00007fad65739000)
libasyncns.so.0 => /usr/lib/x86_64-linux-gnu/libasyncns.so.0 (0x00007fad65534000)
libattr.so.1 => /lib/x86_64-linux-gnu/libattr.so.1 (0x00007fad6532e000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fad65116000)
libselinux.so.1 => /lib/x86_64-linux-gnu/libselinux.so.1 (0x00007fad64ef4000)
libresolv.so.2 => /lib/x86_64-linux-gnu/libresolv.so.2 (0x00007fad64cdd000)
libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007fad64ad9000)
libtasn1.so.3 => /usr/lib/x86_64-linux-gnu/libtasn1.so.3 (0x00007fad648c8000)
libp11-kit.so.0 => /usr/lib/x86_64-linux-gnu/libp11-kit.so.0 (0x00007fad646a8000)
libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007fad64495000)
libXi.so.6 => /usr/lib/x86_64-linux-gnu/libXi.so.6 (0x00007fad64285000)
libnsl.so.1 => /lib/x86_64-linux-gnu/libnsl.so.1 (0x00007fad6406c000)
libFLAC.so.8 => /usr/lib/x86_64-linux-gnu/libFLAC.so.8 (0x00007fad63e3a000)
libvorbisenc.so.2 => /usr/lib/x86_64-linux-gnu/libvorbisenc.so.2 (0x00007fad6396b000)
libvorbis.so.0 => /usr/lib/x86_64-linux-gnu/libvorbis.so.0 (0x00007fad6373d000)
libogg.so.0 => /usr/lib/x86_64-linux-gnu/libogg.so.0 (0x00007fad63536000)
┌─[solomon@Sucker] - [~] - [2013-07-28 04:13:18]
└─[0]
seems to be the same or similar issue as #2740
Run steam --reset in your terminal and it will reset steam's settings and the client will work.
┌─[solomon@Sucker] - [~] - [2013-07-28 12:28:22]
└─[0] steam
Running Steam on debian 64-bit
STEAM_RUNTIME is enabled automatically
Assert( Assertion Failed: nSize != 0 ):/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/tier1/../tier1/utlbuffer.cpp:221
Installing breakpad exception handler for appid(steam)/version(1.0_client)
Uploading dump (out-of-process) [proxy '']
/tmp/dumps/crash_20130728002836_2.dmp
Installing breakpad exception handler for appid(steam)/version(1374006490_client)
Installing breakpad exception handler for appid(steam)/version(1.0_client)
Installing breakpad exception handler for appid(steam)/version(1.0_client)
unlinked 0 orphaned pipes
removing stale semaphore last operated on by process 6216 with name 0eBlobRegistryMutex_54278E4A86B4030E7ACBECA4FA9791F2
removing stale semaphore last operated on by process 6216 with name 0eBlobRegistrySignal_54278E4A86B4030E7ACBECA4FA9791F2
removing stale semaphore last operated on by process 6216 with name 0emSteamEngineInstance
removing stale semaphore last operated on by process 6216 with name 0eSteamEngineLock
Installing breakpad exception handler for appid(steam)/version(1374006490_client)
[0728/002837:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation
/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/tier1/../tier1/utlbuffer.cpp (221) : Assertion Failed: nSize != 0
Assert( Assertion Failed: nSize != 0 ):/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/tier1/../tier1/utlbuffer.cpp:221
Installing breakpad exception handler for appid(steam)/version(1374006490_client)
Uploading dump (out-of-process) [proxy '']
/tmp/dumps/assert_20130728002837_8.dmp
ILocalize::AddFile() failed to load file "resource/vgui_english.txt".
/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/tier1/../tier1/utlbuffer.cpp (221) : Assertion Failed: nSize != 0
ILocalize::AddFile() failed to load file "resource/overlay_english.txt".
Failed to load overlay localization file.
Finished uploading minidump (out-of-process): success = yes
response: CrashID=bp-02e353b1-2429-411c-8d71-f18892130728