I tried to install a game on my Linux laptop while a game was already playing on my Windows box. The Steam client gave me an error dialog with the title #Steam_OtherSessionPlaying_Title, and text of #Steam_OtherSessionPlaying_Text. Which are obviously variable names/template placeholders that did not get rendered out to their contents.

System Settings:

Processor Information:
    Vendor:  GenuineIntel
    CPU Family:  0x6
    CPU Model:  0x2a
    CPU Stepping:  0x7
    CPU Type:  0x0
    Speed:  3200 Mhz
    4 logical processors
    2 physical processors
    HyperThreading:  Supported
    FCMOV:  Supported
    SSE2:  Supported
    SSE3:  Supported
    SSSE3:  Supported
    SSE4a:  Unsupported
    SSE41:  Supported
    SSE42:  Supported

Network Information:
    Network Speed:  

Operating System Version:
    Linux (64 bit)
    Kernel Name:  Linux
    Kernel Version:  3.17.4-1-ARCH
    X Server Vendor:  The X.Org Foundation
    X Server Release:  11602000
    X Window Manager:  Fluxbox
    Steam Runtime Version:  steam-runtime-release_2013-10-23

Video Card:
    Driver:  Intel Open Source Technology Center Mesa DRI Intel(R) Sandybridge Mobile x86/MMX/SSE2

    Driver Version:  3.0 Mesa 10.3.5
    OpenGL Version: 3.0
    Desktop Color Depth: 24 bits per pixel
    Monitor Refresh Rate: 60 Hz
    VendorID:  0x8086
    DeviceID:  0x126
    Number of Monitors:  1
    Number of Logical Video Cards:  1
    Primary Display Resolution:  1920 x 1080
    Desktop Resolution: 1920 x 1080
    Primary Display Size: 13.54" x 7.60"  (15.51" diag)
                                            34.4cm x 19.3cm  (39.4cm diag)
    Primary VRAM Not Detected

Sound card:
    Audio device: Intel CougarPoint HDMI

Memory:
    RAM:  5855 Mb

Miscellaneous:
    UI Language:  English
    LANG:  en_US.UTF-8
    Microphone:  Not set
    Total Hard Disk Space Available:  144434 Mb
    Largest Free Hard Disk Block:  84136 Mb

Installed software:

Recent Failure Reports: