The time is incorrect by one hour when you use the System.TimeZone property in Windows Vista in the Jerusalem time zone during daylight saving time

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When you use the Microsoft .NET Framework 2.0 in Windows Vista, the DateTime.Now property may display results that are incorrect by one hour. This problem occurs if the following conditions are true:
  • Windows Vista is configured to use the Jerusalem time zone.
  • The months contain daylight saving time (DST) transitions.
For example, in 2007, the DateTime.Now property incorrectly reports DST as starting five days early (on March 25 instead of on March 30). Additionally, the DateTime.Now property will incorrectly report DST as ending 14 days late (on September 30 instead of on September 16).

Therefore, .NET Framework programs such as Windows Media Center that are running in Windows Vista will be off by one hour in the Jerusalem time zone during these periods.
This problem occurs because Windows Vista has fixed-date time zone rules for the Jerusalem time zone. The System.TimeZone.CurrentTimeZone property does not handle fixed-date rules correctly. The System.TimeZone.CurrentTimeZone property expects all transition dates to be floating (relative) times. For example, the System.TimeZone.CurrentTimeZone property expects the transition date to be in the following format:
Nth day_of_the_ week in month
Note In Windows Vista, the Jerusalem time zone is the only time zone that uses fixed-date rules.
This update is licensed to you under the terms of the Windows Vista License Agreement.

Update information

The following file is available for download from the Microsoft Download Center:

Windows Vista, 32-bit versions

DownloadDownload the KB940716 package now.

Windows Vista, 64-bit versions

DownloadDownload the KB940716 package now.

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:
119591 How to obtain Microsoft support files from online services
Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.


You must have the Microsoft .NET Framework 2.0 installed to apply this update.

Restart requirement

You do not have to restart the computer after you install this update.

Update replacement information

This update does not replace any other update.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
More information
For more information about software update terminology, 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

Article ID: 940716 - Last Review: 01/16/2015 09:45:41 - Revision: 4.0

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