BsoD: PFN_LIST_CORRUPT

Windows Vista 64bit.

Every once in a month of continuous normal operation, without doing anything in particular, I get one of these.

Code:

Microsoft (R) Windows Debugger Version 6.9.0003.113 AMD64
Copyright (c) Microsoft Corporation. All rights reserved.


Loading Dump File [C:\Windows\MEMORY.DMP]
Kernel Summary Dump File: Only kernel address space is available

Symbol search path is: SRV*C:\Program Files\Debugging Tools for Windows (x64)\sym*http://msdl.microsoft.com/download/symbols
Executable search path is: 
Windows Server 2008 Kernel Version 6001 (Service Pack 1) MP (2 procs) Free x64
Product: WinNt, suite: TerminalServer SingleUserTS
Built by: 6001.18145.amd64fre.vistasp1_gdr.080917-1612
Kernel base = 0xfffff800`01e1a000 PsLoadedModuleList = 0xfffff800`01fdfdb0
Debug session time: Mon Dec  8 21:29:26.926 2008 (GMT+2)
System Uptime: 1 days 5:51:08.225
Loading Kernel Symbols
........................................................................................................................................................................
Loading User Symbols

Loading unloaded module list
....................
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*                        Bugcheck Analysis                                    *
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Use !analyze -v to get detailed debugging information.

BugCheck 4E, {8d, 3004a, 5530000, fffff880011dc341}

Probably caused by : memory_corruption ( nt!MmZeroPageThread+4d7 )

Followup: MachineOwner
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1: kd> !analyze -v
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*                        Bugcheck Analysis                                    *
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PFN_LIST_CORRUPT (4e)
Typically caused by drivers passing bad memory descriptor lists (ie: calling
MmUnlockPages twice with the same list, etc).  If a kernel debugger is
available get the stack trace.
Arguments:
Arg1: 000000000000008d, 
Arg2: 000000000003004a
Arg3: 0000000005530000
Arg4: fffff880011dc341

Debugging Details:
------------------


BUGCHECK_STR:  0x4E_8d

DEFAULT_BUCKET_ID:  VISTA_DRIVER_FAULT

PROCESS_NAME:  System

CURRENT_IRQL:  2

LAST_CONTROL_TRANSFER:  from fffff80001e635b7 to fffff80001e6f350

STACK_TEXT:  
fffffa60`005afc78 fffff800`01e635b7 : 00000000`0000004e 00000000`0000008d 00000000`0003004a 00000000`05530000 : nt!KeBugCheckEx
fffffa60`005afc80 fffff800`0225bb1e : 01c6fe83`00000000 fffffa80`00000000 00000000`00000000 fffff800`022aa000 : nt!MmZeroPageThread+0x4d7
fffffa60`005afd20 fffff800`02091ff3 : 00000000`10002000 fffff800`01ea9539 00000000`00000010 00000000`00000286 : nt!Phase1Initialization+0xe
fffffa60`005afd50 fffff800`01ea9546 : fffff800`01f8e680 fffffa80`0188dbb0 fffff800`01f93b80 fffff800`0081b358 : nt!PspSystemThreadStartup+0x57
fffffa60`005afd80 00000000`00000000 : 00000000`00000000 00000000`00000000 00000000`00000000 00000000`00000000 : nt!KxStartSystemThread+0x16


STACK_COMMAND:  kb

FOLLOWUP_IP: 
nt!MmZeroPageThread+4d7
fffff800`01e635b7 cc              int     3

SYMBOL_STACK_INDEX:  1

SYMBOL_NAME:  nt!MmZeroPageThread+4d7

FOLLOWUP_NAME:  MachineOwner

MODULE_NAME: nt

DEBUG_FLR_IMAGE_TIMESTAMP:  48d1ba35

IMAGE_NAME:  memory_corruption

FAILURE_BUCKET_ID:  X64_0x4E_8d_nt!MmZeroPageThread+4d7

BUCKET_ID:  X64_0x4E_8d_nt!MmZeroPageThread+4d7

Followup: MachineOwner

I scanned both video RAM and motherboard RAM for faults. No problems found. HDD SMART not reporting any issues either. My biggest problem is that it ain't pointing me to a file I could suspect. Can you help me track it down?