X server crashes upon starting a battle

Almost immediately after starting a battle the display I was using closed and kicked me back to the login screen. A possibly enlightening snippet from /var/log/messages suggests a segfault may be the cause:

Code:

Oct 29 01:40:39 salt kdm[2993]: X server for display :0 terminated unexpectedly
Oct 29 01:40:39 salt polkitd[2767]: Unregistered Authentication Agent for unix-session:/org/freedesktop/ConsoleKit/Session99 (system bus name :1.912, object path /org/kde/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
Oct 29 01:20:26 salt kernel: CoherentUI_Host[25858]: segfault at 0 ip 000000000047330a sp 00007fffeb9c0890 error 4 in CoherentUI_Host[400000+4334000]
Oct 29 01:40:39 salt kdm[25067]: :0[25067]: pam_unix(kde:session): session closed for user wetzker

Impressive. Which Linux distro do you use? And which graphics drivers?

I had forgotten my go-to solution of disabling the steam overlay, doing so seems to have stopped the problem. It's unusual because when the overlay causes problems it mostly hurts performance or has the game hang, I've never seen a crash-to-desktop-and-then-crash-the-desktop issue before.

Distro: Linux 3.14.14-gentoo
Driver Version: 4.5.0 NVIDIA 346.47

Info from steam client:

Code:

Processor Information:
    Vendor:  AuthenticAMD
    CPU Family:  0x15
    CPU Model:  0x2
    CPU Stepping:  0x0
    CPU Type:  0x0
    Speed:  3500 Mhz
    6 logical processors
    6 physical processors
    HyperThreading:  Unsupported
    FCMOV:  Supported
    SSE2:  Supported
    SSE3:  Supported
    SSSE3:  Supported
    SSE4a:  Supported
    SSE41:  Supported
    SSE42:  Supported
   
Network Information:
    Network Speed: 
   
Operating System Version:
    Linux 3.10 (64 bit)
    Kernel Name:  Linux
    Kernel Version:  3.14.14-gentoo
    X Server Vendor:  The X.Org Foundation
    X Server Release:  11604000
    X Window Manager:  KWin
    Steam Runtime Version:  steam-runtime-release_2015-06-12
   
Video Card:
    Driver:  NVIDIA Corporation GeForce GTX 650/PCIe/SSE2

    Driver Version:  4.5.0 NVIDIA 346.47
    OpenGL Version: 4.5
    Desktop Color Depth: 24 bits per pixel
    Monitor Refresh Rate: 60 Hz
    VendorID:  0x10de
    DeviceID:  0xfc6
    Number of Monitors:  1
    Number of Video Cards Not Detected
    Primary Display Resolution:  1920 x 1080
    Desktop Resolution: 1920 x 1080
    Primary Display Size: 18.74" x 10.51"  (21.46" diag)
                                            47.6cm x 26.7cm  (54.5cm diag)
    Primary Bus: PCI Express 16x
    Primary VRAM: 1024 MB
    Supported MSAA Modes:  2x 4x 8x 16x
   
Sound card:
    Audio device: Realtek ALC887-VD
   
Memory:
    RAM:  16061 Mb
   
Miscellaneous:
    UI Language:  English
    LANG:  none
    Microphone:  Not set
    Total Hard Disk Space Available:  187659 Mb
    Largest Free Hard Disk Block:  122451 Mb
   
Installed software:
   
Recent Failure Reports:
    Thu Oct 22 06:31:06 2015 GMT: file ''/tmp/dumps/assert_20151022013057_124.dmp'', upload yes: ''CrashID=bp-582cb250-7b8b-429a-867b-8bc592151021''