Comment # 6 on bug 1029999 from Fabian Vogt

> If A is active and has WLAN activated and linked to a AP
> If B logged in all ok
> If C logged in: in the moment you activate the BT and move the mouse, this will segfault (no matter while with sddm or lightdm) the whole system. 

That means an event somehow gets relayed to all sessions and all three
ksmservers crash, or the stack below (X, kernel) screws up.
Please try to get all system logs when it happens (save_y2logs might be
suitable here)

(In reply to Stakanov Schufter from comment #5)
> Created attachment 718014 [details]
> KSM server crash realted to the present bug
> 
> Last bit of info: 
> although you can work without crashes during apparently an unlimited time,
> WLAN crashes again when you choose to disconnect the BT mouse. 
> I was noting a KSM server crash and saved the backtrace (see attachment). It
> maz be related or not, but I had the impression it was. The crash during
> disconnecting does not terminate the session as the connecting event but you
> have the KSM server crash.

That ksmserver crash happens during shutdown of the session, so it can't be
related.