Hyper-V BSOD Windows Server 2012 R2 vhdmp.sys

On a Hyper-V server (ProLiant DL380p Gen8) that has been running for 8 months, I have suddenly had two BSOD's out of the blue ;-)

19 Dec 02:06

29 Dec 21:07

Here is the latest dump.. the only slightly different thing that has happened recently is that there is now a Windows 7 VM of SpiceWorks running as a VM

Any ideas?

MODULE_NAME: vhdmp

FAULTING_MODULE: fffff801dce0a000 nt

DEBUG_FLR_IMAGE_TIMESTAMP:  52e848da

EXCEPTION_RECORD:  ffffd000255353b8 -- (.exr 0xffffd000255353b8)
ExceptionAddress: fffff80044eae154 (vhdmp+0x0000000000009154)
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 0000000000000000
   Parameter[1]: ffffffffffffffff
Attempt to read from address ffffffffffffffff

CONTEXT:  ffffd00025534bc0 -- (.cxr 0xffffd00025534bc0;r)
rax=00000000726f6673 rbx=ffffe8002eb6e080 rcx=ffffe800258ed4b0
rdx=ffffe800258ed4b0 rsi=ffffe8002eb6d000 rdi=ffffe800258ed4b0
rip=fffff80044eae154 rsp=ffffd000255355f0 rbp=ffffd00025535670
 r8=510000000000082f  r9=000000000000002f r10=fffff801dd5995b0
r11=0000000000000000 r12=0000000000000000 r13=0000000000000001
r14=ffffe8002615d040 r15=ffffe80025980750
iopl=0         nv up ei pl nz na pe nc
cs=0010  ss=0018  ds=002b  es=002b  fs=0053  gs=002b             efl=00010202
vhdmp+0x9154:
fffff800`44eae154 ff5338          call    qword ptr [rbx+38h] ds:002b:ffffe800`2eb6e0b8=????????????????
Last set context:
rax=00000000726f6673 rbx=ffffe8002eb6e080 rcx=ffffe800258ed4b0
rdx=ffffe800258ed4b0 rsi=ffffe8002eb6d000 rdi=ffffe800258ed4b0
rip=fffff80044eae154 rsp=ffffd000255355f0 rbp=ffffd00025535670
 r8=510000000000082f  r9=000000000000002f r10=fffff801dd5995b0
r11=0000000000000000 r12=0000000000000000 r13=0000000000000001
r14=ffffe8002615d040 r15=ffffe80025980750
iopl=0         nv up ei pl nz na pe nc
cs=0010  ss=0018  ds=002b  es=002b  fs=0053  gs=002b             efl=00010202
vhdmp+0x9154:
fffff800`44eae154 ff5338          call    qword ptr [rbx+38h] ds:002b:ffffe800`2eb6e0b8=????????????????
Resetting default scope

DEFAULT_BUCKET_ID:  WIN8_DRIVER_FAULT

BUGCHECK_STR:  0x24

CURRENT_IRQL:  0

ANALYSIS_VERSION: 6.3.9600.17298 (debuggers(dbg).141024-1500) amd64fre

LAST_CONTROL_TRANSFER:  from fffff80044ed7d98 to fffff80044eae154

STACK_TEXT:  
ffffd000`255355f0 fffff800`44ed7d98 : ffffd000`25535660 ffffe800`2eb6d000 00000000`00000010 ffffc001`206c644d : vhdmp+0x9154
ffffd000`25535620 fffff801`dcea9378 : ffffe800`26bc7730 ffffe800`26bc7700 ffffe800`26bc79fb ffffc001`6bbe0010 : vhdmp+0x32d98
ffffd000`25535690 fffff800`43422130 : ffffe800`2ef1b000 00000000`00000001 ffffe800`2ef1b018 ffffe800`26bc7730 : nt!IofCompleteRequest+0x594
ffffd000`255357a0 fffff800`4341ea58 : 00000000`00000000 ffffd000`25535a40 ffffc001`734fd140 00000000`00000048 : Ntfs+0x1b130
ffffd000`255357d0 fffff800`4340ea89 : ffffe800`2ef1b018 ffffd000`25535a40 00000000`00000000 ffffe800`2ef1b018 : Ntfs+0x17a58
ffffd000`25535a00 fffff801`dce5dadb : fffff800`430cb100 fffff800`4340e860 ffffe800`2ef1b018 ffffe800`28e2f540 : Ntfs+0x7a89
ffffd000`25535b50 fffff801`dced9794 : 00000000`00000000 ffffe800`28e2f540 ffffe800`28e2f540 ffffe000`5de2a380 : nt!RtlSidHashLookup+0x228f
ffffd000`25535c00 fffff801`dcf645c6 : ffffd001`64a80180 ffffe800`28e2f540 ffffd001`64a8c7c0 00000000`00000000 : nt!KeAcquireSpinLockRaiseToDpc+0x1a4
ffffd000`25535c60 00000000`00000000 : ffffd000`25536000 ffffd000`25530000 00000000`00000000 00000000`00000000 : nt!KeSynchronizeExecution+0x59d6


FOLLOWUP_IP: 
vhdmp+9154
fffff800`44eae154 ff5338          call    qword ptr [rbx+38h]

SYMBOL_STACK_INDEX:  0

SYMBOL_NAME:  vhdmp+9154

FOLLOWUP_NAME:  MachineOwner

IMAGE_NAME:  vhdmp.sys

STACK_COMMAND:  .cxr 0xffffd00025534bc0 ; kb

BUCKET_ID:  WRONG_SYMBOLS

FAILURE_BUCKET_ID:  WRONG_SYMBOLS

ANALYSIS_SOURCE:  KM

FAILURE_ID_HASH_STRING:  km:wrong_symbols

FAILURE_ID_HASH:  {70b057e8-2462-896f-28e7-ac72d4d365f8}

Followup: MachineOwner
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