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Windows 7: Occasional BSoD a few times per day, unsure of cause

02 Jul 2014   #1

Windows 7 Home Premium
Occasional BSoD a few times per day, unsure of cause

This has only been happening for the past few days and I haven't yet noticed any link between the times it's happened, so I don't have any idea what may be causing it. :[

I've attached both of the file options, so hopefully they'll be of use. Thank you so much in advance!

My System SpecsSystem Spec
02 Jul 2014   #2

W7 Pro x64 SP1 | W10 Pro IP x64 | W8.1 Pro x64 VM | Linux Mint VM

MalwareBytes had been flagged.

*                                                                             *
*                        Bugcheck Analysis                                    *
*                                                                             *

Use !analyze -v to get detailed debugging information.

BugCheck 19, {20, fffffa8007868db0, fffffa8007868dd0, 4020008}

*** WARNING: Unable to verify timestamp for mwac.sys
*** ERROR: Module load completed but symbols could not be loaded for mwac.sys
Probably caused by : fwpkclnt.sys ( fwpkclnt!FwpsConstructIpHeaderForTransportPacket0+20a )

Followup: MachineOwner
Make sure it's updated. If the problem persists when MBAM is completely updated then uninstall it and test.

1: kd> lmvm mwac
start             end                 module name
fffff880`0e07c000 fffff880`0e08e000   mwac     T (no symbols)           
    Loaded symbol image file: mwac.sys
    Image path: \??\C:\Windows\system32\drivers\mwac.sys
    Image name: mwac.sys
    Timestamp:        Tue Mar 04 21:47:13 2014 (531649E1)
    CheckSum:         00010A4A
    ImageSize:        00012000
    Translations:     0000.04b0 0000.04e4 0409.04b0 0409.04e4
Uninstall DaemonTools, a known cause of BSODs.

1. Uninstall Daemon Tools.
2. Download the SPTD standalone installer and follow these steps:
3. Double click the executable to open it
4. Click the button shown below

If the button it is grayed out, as shown in the image, there is no more SPTD installation on your system, and you can just close the window.
My System SpecsSystem Spec
02 Jul 2014   #3


Not to take Boozad's post away from him but I'd like to add to his post and I think I may know what might be/add to the cause of your crashes.

BugCheck 19, {20, fffffa8007868db0, fffffa8007868dd0, 4020008}
This bugcheck indicates a pool header was already corrupt at the time of the request and the culprit has escaped the scene of the crime, lets look into this further.

1: kd> !pool fffffa8007868db0
Pool page fffffa8007868db0 region is Nonpaged pool
 fffffa8007868000 size:   d0 previous size:    0  (Allocated)  MmCa
 fffffa80078680d0 size:   c0 previous size:   d0  (Allocated)  FMsl
 fffffa8007868190 size:   50 previous size:   c0  (Allocated)  VadS
 fffffa80078681e0 size:  1e0 previous size:   50  (Free)       AfdE
 fffffa80078683c0 size:   d0 previous size:  1e0  (Allocated)  MmCa
 fffffa8007868490 size:   80 previous size:   d0  (Allocated)  KPXY
 fffffa8007868510 size:   40 previous size:   80  (Allocated)  ReTa
 fffffa8007868550 size:   80 previous size:   40  (Allocated)  Even (Protected)
 fffffa80078685d0 size:   30 previous size:   80  (Free)       ReEv
 fffffa8007868600 size:   40 previous size:   30  (Allocated)  WfpH
 fffffa8007868640 size:   d0 previous size:   40  (Allocated)  MmCa
 fffffa8007868710 size:  160 previous size:   d0  (Allocated)  Ntfx
 fffffa8007868870 size:  240 previous size:  160  (Free)       pppt
 fffffa8007868ab0 size:  150 previous size:  240  (Allocated)  File (Protected)
 fffffa8007868c00 size:   20 previous size:  150  (Free )  WfpH
 fffffa8007868c20 size:   90 previous size:   20  (Allocated)  Vad 
 fffffa8007868cb0 size:   80 previous size:   90  (Allocated)  Even (Protected)
 fffffa8007868d30 size:   80 previous size:   80  (Allocated)  CM44 Process: fffffa800372bb30
*fffffa8007868db0 size:   20 previous size:   80  (Free ) *Ipng
		Pooltag Ipng : IP Generic buffers (Address, Interface, Packetize, Route allocations), Binary : tcpip.sys

fffffa8007868dd0 doesn't look like a valid small pool allocation, checking to see
if the entire page is actually part of a large page allocation...

GetUlongFromAddress: unable to read from fffff8000287aa38
Unable to get pool big page table. Check for valid symbols.
fffffa8007868dd0 is not valid pool. Checking for freed (or corrupt) pool
Bad allocation size @fffffa8007868dd0, zero is invalid

*** An error (or corruption) in the pool was detected;
*** Attempting to diagnose the problem.
*** Use !poolval fffffa8007868000 for more details.

Pool page [ fffffa8007868000 ] is __inVALID.

Analyzing linked list...
[ fffffa8007868db0 --> fffffa8007868e50 (size = 0xa0 bytes)]: Corrupt region

Scanning for single bit errors...

None found
So the pool used is invalid, now it has a network pool tag which helps us a bit here.

1: kd> dt_POOL_HEADER fffffa8007868db0
   +0x000 PreviousSize     : 0y00001000 (0x8)
   +0x000 PoolIndex        : 0y00000000 (0)
   +0x000 BlockSize        : 0y00000010 (0x2)
   +0x000 PoolType         : 0y00000100 (0x4)
   +0x000 Ulong1           : 0x4020008
   +0x004 PoolTag          : 0x676e7049
   +0x008 ProcessBilled    : 0xfffffa80`08ed12a0 _EPROCESS
   +0x008 AllocatorBackTraceIndex : 0x12a0
   +0x00a PoolTagHash      : 0x8ed
As far as I know, that index is wrong, I believe non paged pool should be indicated with 1 which I may or may not be right, I'm pretty sure I am though.

1: kd> dc fffffa8007868db0 fffffa8007868db0+20
fffffa80`07868db0  04020008 676e7049 08ed12a0 fffffa80  ....Ipng........
fffffa80`07868dc0  00110064 61440800 61651120 0900a8c0  d.....Da .ea....
fffffa80`07868dd0  ff00a8c0
It looks cut off, so part of the page is missing, very strange, given that its network related and Malwarebytes is being blamed I have a hunch what it could be.

*** WARNING: Unable to verify timestamp for mwac.sys
*** ERROR: Module load completed but symbols could not be loaded for mwac.sys
Probably caused by : fwpkclnt.sys ( fwpkclnt!FwpsConstructIpHeaderForTransportPacket0+20a )
Well we can see Malwarebytes is conflicting with a network device and looking at the network devices on the system I see this as a troublemaker...

Name	[00000013] avast! Firewall NDIS Filter Miniport
An Avast firewall, that's probably the cause of the conflict.
My System SpecsSystem Spec


 Occasional BSoD a few times per day, unsure of cause

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