BSOD 0x9F in NTOSKRNL.EXE

I'm getting somewhat frequent BSODs these days.

WinDbg reports:

*******************************************************************************

*                                                                             *

*                        Bugcheck Analysis                                    *

*                                                                             *

*******************************************************************************

Use !analyze -v to get detailed debugging information.

BugCheck 9F, {4, 12c, 86a6c340, 809b4b54}

Implicit thread is now 86a6c340

Probably caused by : ntkrpamp.exe ( nt!KiSwapContext+19 )

Followup: MachineOwner

---

0: kd> !analyze -v

*******************************************************************************

*                                                                             *

*                        Bugcheck Analysis                                    *

*                                                                             *

*******************************************************************************

DRIVER_POWER_STATE_FAILURE (9f)

A driver has failed to complete a power IRP within a specific time (usually 10 minutes).

Arguments:

Arg1: 00000004, The power transition timed out waiting to synchronize with the Pnp

 subsystem.

Arg2: 0000012c, Timeout in seconds.

Arg3: 86a6c340, The thread currently holding on to the Pnp lock.

Arg4: 809b4b54, nt!TRIAGE_9F_PNP on Win7

Debugging Details:

---

Implicit thread is now 86a6c340

DRVPOWERSTATE_SUBCODE:  4

FAULTING_THREAD:  86a6c340

DEFAULT_BUCKET_ID:  WIN8_DRIVER_FAULT

BUGCHECK_STR:  0x9F

PROCESS_NAME:  System

CURRENT_IRQL:  2

LAST_CONTROL_TRANSFER:  from 81bfb22f to 81ba3699

STACK_TEXT: 

d88f7aec 81bfb22f 00002000 86a6c398 86a6c340 nt!KiSwapContext+0x19

d88f7b60 81bfd058 86a6c340 86a6c420 00000002 nt!KiCommitThreadWait+0x280

d88f7bfc 81c19a81 84ef4710 0000001b 00000000 nt!KeWaitForSingleObject+0x26c

d88f7c60 81c02406 81c54ee0 84ef4710 81c39578 nt!ExpWaitForResource+0xd2

d88f7ca8 81d04d68 81c54ee0 00000001 81c39578 nt!ExAcquireResourceExclusiveLite+0x191

d88f7cc4 81ad36f9 00000001 81c39578 86a6c340 nt!PpDevNodeLockTree+0x43

d88f7d1c 81c01c95 00000000 86a6c340 00000000 nt!PnpDeviceActionWorker+0x3d

d88f7d74 81ae5aaa 00010000 c8c30dc3 00000000 nt!ExpWorkerThread+0x111

d88f7db0 81ba3f19 81c01b88 00010000 00000000 nt!PspSystemThreadStartup+0x4a

00000000 00000000 00000000 00000000 00000000 nt!KiThreadStartup+0x19

STACK_COMMAND:  .thread 0xffffffff86a6c340 ; kb

FOLLOWUP_IP:

nt!KiSwapContext+19

81ba3699 8b2c24          mov     ebp,dword ptr [esp]

SYMBOL_STACK_INDEX:  0

SYMBOL_NAME:  nt!KiSwapContext+19

FOLLOWUP_NAME:  MachineOwner

MODULE_NAME: nt

IMAGE_NAME:  ntkrpamp.exe

DEBUG_FLR_IMAGE_TIMESTAMP:  513809e8

BUCKET_ID_FUNC_OFFSET:  19

FAILURE_BUCKET_ID:  0x9F_4_nt!KiSwapContext

BUCKET_ID:  0x9F_4_nt!KiSwapContext

Followup: MachineOwner

---

The file ntoskrnl.exe is dated March 7 and has the following version information:

c:/windows/system32/ntoskrnl.exe:

File Version:  6.2.9200.16551

Product Version: 6.2.9200.16551

File Flags:  

File OS:  NT_WINDOWS32

File Type:  APP

Language: English (United States), Code Page: Unicode

 CompanyName: Microsoft Corporation

 FileDescription: NT Kernel & System

 FileVersion: 6.2.9200.16551 (win8_gdr.130306-1502)

 InternalName: ntkrpamp.exe

 LegalCopyright: © Microsoft Corporation. All rights reserved.

 OriginalFilename: ntkrpamp.exe

 ProductName: Microsoft® Windows® Operating System

 ProductVersion: 6.2.9200.16551

I have a full memory dump available.

How should I troubleshoot this (other than the tedious msconfig / disable stuff / enable stuff /... process)?