Random crash during shutdown

R24718 on QEMU 0.8.2. Trace:

Assertion 'FALSE' failed at ntoskrnl\ke\thrdschd.c line 223

• • • Fatal System Error: 0x0000001e
      (0x80000003,0x800831F2,0x81511400,0x9FDCAB68)

<ntoskrnl.exe:2571 (ntoskrnl/ke/bug.c:1078 (KeBugCheckEx))>
<ntoskrnl.exe:76a96 (ntoskrnl/ke/i386/exp.c:807 (KiDispatchException))>
<ntoskrnl.exe:785c7 (ntoskrnl\ke\i386\trap.s:722 (CommonDispatchException))>
<ntoskrnl.exe:831f3 (lib\rtl\i386\debug_asm.S:31 (DbgBreakPoint@0))>
<ntoskrnl.exe:731a (ntoskrnl/ke/thrdschd.c:236 (KiReadyThread))>
<ntoskrnl.exe:3b09 (ntoskrnl/ke/event.c:288 (KeSetEventBoostPriority))>
<ntoskrnl.exe:1a2d4 (ntoskrnl/ex/fmutex.c:82 (ExReleaseFastMutexUnsafeAndLeaveCriticalRegion))>
<win32k.sys:49ae8 (./subsystems/win32/win32k/ntuser/ntuser.c:115 (UUserLeave))>
<win32k.sys:413bc (subsystems/win32/win32k/main/dllmain.c:312 (Win32kThreadCallback))>
<ntoskrnl.exe:62ece (ntoskrnl/ps/kill.c:645 (PspExitThread))>
<ntoskrnl.exe:636ef (ntoskrnl/ps/kill.c:843 (PsExitSpecialApc))>
<ntoskrnl.exe:147a (ntoskrnl/ke/apc.c:467 (KiDeliverApc))>
<ntoskrnl.exe:77ef6 (ntoskrnl\ke\i386\trap.s:337 (KiServiceExit))>

Still don't know how to reproduce it. Just FYI.