While reviewing my Event Log history, I came across this message. What does it mean?

Log Name: Security
Source: Microsoft-Windows-Security-Auditing
Date: 7/11/2010 5:04:14 PM
Event ID: 6281
Task Category: System Integrity
Level: Information
Keywords: Audit Failure
User: N/A
Code Integrity determined that the page hashes of an image file are not valid. The file could be improperly signed without page hashes or corrupt due to unauthorized modification. The invalid hashes could indicate a potential disk device error.

File Name: \Device\HarddiskVolume2\Program Files\CheckPoint\ZAForceField\Plugins\ISWSHEX.dll
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<Provider Name="Microsoft-Windows-Security-Auditing" Guid="{54849625-5478-4994-A5BA-3E3B0328C30D}" />
<TimeCreated SystemTime="2010-07-11T22:04:14.511954200Z" />
<Correlation />
<Execution ProcessID="4" ThreadID="64" />
<Security />
<Data Name="param1">\Device\HarddiskVolume2\Program Files\CheckPoint\ZAForceField\Plugins\ISWSHEX.dll</Data>

OS Name Microsoft Windows 7 Home Premium
Version 6.1.7600 Build 7600
Other OS Description Not Available
OS Manufacturer Microsoft Corporation
System Name
System Manufacturer Hewlett-Packard
System Model HP Pavilion dv4 Notebook PC
System Type x64-based PC
Processor AMD Turion(tm) II Dual-Core Mobile M520, 2300 Mhz, 2 Core(s), 2 Logical Processor(s)
BIOS Version/Date Insyde F.17, 12/10/2009
SMBIOS Version 2.6
Windows Directory C:\Windows
System Directory C:\Windows\system32
Boot Device \Device\HarddiskVolume1
Locale United States
Hardware Abstraction Layer Version = "6.1.7600.16385"
User Name
Time Zone Central Daylight Time
Installed Physical Memory (RAM) 4.00 GB
Total Physical Memory 3.75 GB
Available Physical Memory 2.31 GB
Total Virtual Memory 7.49 GB
Available Virtual Memory 5.56 GB
Page File Space 3.75 GB
Page File C:\pagefile.sys

ZoneAlarm File version or Product version

I have two (2) ISWSHEX.dll(s). Both have modified dates of 5/26/10 8:35 AM. One is 626 KB and the other 1,022 KB. I scanned them with Avast! and it returned "no threat found." The paths are ...\CheckPoint\ZAForceField\WOW64 and ...\CheckPoint\ZAForceField respectively.

According to VeriSign certificate status on both files, "This certificate is OK."

By the way, according to my events log, this event has occured 825 times since 3/9/2010.