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Article ID: 934274 - Last Review: January 16, 2015 - Revision: 3.0

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On a computer that is running Windows Vista, a 6.6.x.x version of the Cdosys.dll file is installed. On this computer, you apply the daylight saving time (DST) updates that are described in the following Microsoft Knowledge Base article:
933360  ( ) August 2007 cumulative time zone update for Microsoft Windows operating systems
After you apply these updates, applications that use Collaboration Data Objects (CDO) process the current time in the old version of the local time zone instead of in the updated version of the local time zone. Therefore, the applications may display the incorrect time.

For example, you may expect an e-mail message to have the following time stamp when you send it at 9:37 P.M. on March 11, 2007:
11 March 2007 21:37 (GMT-7)
However, the message displays the following time stamp:
11 March 2007 20:37 (GMT-7)


In Windows Vista, the Cdosys.dll module compares the current Windows time zone to a hard-coded time zone array. When you apply the DST updates, the Windows time zone changes. Therefore, the Cdosys.dll module cannot find a match for the current time zone in the hard-coded array. In this situation, the Cdosys.dll module uses a similar time zone in the hard-coded array instead of the local time zone.


Service pack information

To resolve this problem, obtain the latest service pack for Windows Vista. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
935791  ( ) How to obtain the latest Windows Vista service pack

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: (
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


No prerequisites are required.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.
Windows Vista, x86-based versions
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatform
Update.mumNot Applicable1,78609-Aug-200715:46Not Applicable
X86_73b8e07a1d28cc8ff8e01bbf656b2fc5_31bf3856ad364e35_6.0.6000.20657_none_ced0e396f39d58ce.manifestNot Applicable69409-Aug-200715:46Not Applicable
X86_microsoft-windows-cdosys_31bf3856ad364e35_6.0.6000.20657_none_1cba4ec9417dac29.manifestNot Applicable58,41209-Aug-200715:46Not Applicable
Windows Vista, 64-bit versions
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatform
Amd64_e8399d420615de2c5903bfff4f2cadb7_31bf3856ad364e35_6.0.6000.20657_none_ad1de84f4ff99d13.manifestNot Applicable1,03609-Aug-200715:46Not Applicable
Amd64_microsoft-windows-cdosys_31bf3856ad364e35_6.0.6000.20657_none_78d8ea4cf9db1d5f.manifestNot Applicable58,45209-Aug-200715:50Not Applicable
Update.mumNot Applicable2,00809-Aug-200715:46Not Applicable


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Vista Service Pack 1.


For more information, click the following article number to view the article in the Microsoft Knowledge Base:
824684  ( ) Description of the standard terminology that is used to describe Microsoft software updates

  • Windows Vista Ultimate
  • Windows Vista Home Premium
  • Windows Vista Home Basic
  • Windows Vista Enterprise
  • Windows Vista Business
  • Windows Vista Business 64-bit Edition
  • Windows Vista Ultimate 64-bit Edition
  • Windows Vista Home Premium 64-bit Edition
  • Windows Vista Home Basic 64-bit Edition
  • Windows Vista Enterprise 64-bit Edition
kbnosurvey kbarchive kbautohotfix kbvistasp1fix kbwinvistapostrtmfix kbexpertiseinter kbbug kbfix kbHotfixServer kbqfe KB934274
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