Steam won't run with "An instance of steam is already running on this computer"

[gedia]

I keep getting this error whenever I try running steam, both with STEAM_RUNTIME=0 and =1. Here's output from the console:

~ $ STEAM_RUNTIME=1 steam --reset

/home/gd/.local/share/Steam/steam.sh: line 475: no match: ssfn*
Running Steam on gentoo 2.2 64-bit
STEAM_RUNTIME is enabled by the user
Installing breakpad exception handler for appid(steam)/version(1459463254)
Installing breakpad exception handler for appid(steam)/version(1459463254)
Assert( Assertion Failed: Function not implemented ):threadtools.cpp:1804

Installing breakpad exception handler for appid(steam)/version(1459463254)
crash_20160411073313_4.dmp[3073]: Uploading dump (out-of-process)
/tmp/dumps/crash_20160411073313_4.dmp
Installing breakpad exception handler for appid(steam)/version(1459463254)
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 72: non-double matrix element
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 72: non-double matrix element
Fontconfig warning: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 80: saw unknown, expected number
[0411/073313:ERROR:main_delegate.cc(777)] Could not load cef_extensions.pak
[0411/073313:ERROR:browser_main_loop.cc(203)] Running without the SUID sandbox! See https://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment for more information on developing with the sandbox on.
Installing breakpad exception handler for appid(steamwebhelper)/version(20160331191033)
Installing breakpad exception handler for appid(steamwebhelper)/version(1459451433)
[0411/073313:ERROR:main_delegate.cc(777)] Could not load cef_extensions.pak
Installing breakpad exception handler for appid(steamwebhelper)/version(20160331191033)
Installing breakpad exception handler for appid(steamwebhelper)/version(1459463254)
Installing breakpad exception handler for appid(steamwebhelper)/version(1459463254)
crash_20160411073313_4.dmp[3073]: Finished uploading minidump (out-of-process): success = yes
crash_20160411073313_4.dmp[3073]: response: CrashID=bp-a6f2b752-4ec4-4081-8544-412a22160410
crash_20160411073313_4.dmp[3073]: file ''/tmp/dumps/crash_20160411073313_4.dmp'', upload yes: ''CrashID=bp-a6f2b752-4ec4-4081-8544-412a22160410''
threadtools.cpp (1804) : Assertion Failed: Function not implemented
Generating new string page texture 4: 256x256, total string texture memory is 262,14 KB
Generating new string page texture 5: 384x256, total string texture memory is 655,36 KB
Generating new string page texture 6: 48x256, total string texture memory is 704,51 KB
[2016-04-11 07:33:13] Startup - updater built Mar 31 2016 19:10:48
[2016-04-11 07:33:13] Verifying installation...
[2016-04-11 07:33:13] Verification complete
threadtools.cpp (1804) : Assertion Failed: Function not implemented
threadtools.cpp (1404) : Assertion Failed: semaphore creation failed Invalid argument
[2016-04-11 07:33:21] Shutdown

On the X front, a steam dialog box appears with the error "An instance of steam is already running on this computer, under a different user account". Naturally running ps aux immediately before launching steam reveals no running processes...

I'm on live mesa and xf86-video-intel packages. GPU is intel skylake.

Any one else experiencing this? Please let me know if I can provide more debug info....

[anyc]

HI,

/home/gd/.local/share/Steam/steam.sh: line 475: no match: ssfn* already looks wrong. Can you paste this file somewhere?