Introduction

The U.S. Energy Policy Act of 2005, passed by the U.S. Congress July, 2005, extended Daylight Saving Time (DST) in the U.S. by approximately four weeks. As a result, beginning in 2007, DST will start three weeks earlier on March 11, 2007, and end one week later on November 4, 2007, resulting in a new DST period that is four weeks longer than previously observed. These four weeks are referred to in this article as the "extended DST period". 

Unless certain updates are applied to your computer, it is possible that the time zone settings for your computer's system clock may be incorrect during this four week period. This depends on where you live and which time zone you have selected. 

When your time zone settings are incorrect your clock may be off by one hour, and certain applications running on your Windows based computer may not display the correct time. To address this, Microsoft is providing many free updates and tools that will update your system automatically.

The change in DST will have an effect on many automated and technology reliant products. Individual consumers, small to medium size businesses, and large enterprises may be affected by the new change in time. Computer-system related issues include, for example:

• Calendar / scheduling applications
• Date / time calculations (current and historical)
• Transaction logging (UTC vs. Local Time)
• Tariff billing applications

In many cases, making the necessary changes to accommodate the new DST legislation will be a relatively minor task. Users may need to manually adjust the time on their devices when the change occurs. In other cases, more substantial efforts may be required. In some cases, systems and applications may need to be updated directly, while in others, the application may simply inherit or "read" the date and time information from the underlying system that it resides on so the changes need only be made to that underlying system. Given the broad range of technology in use today-and the integration of systems between customers, vendors, and partners-business and IT managers should determine what actions should be taken to mitigate the affects of DST 2007 on their organizations. 

Microsoft products affected by 2007 DST changes

Several Microsoft products are affected by DST. Updates and tools to address the DST change are being developed and tested for these products. Some of them are currently available, with the remainder scheduled to be released through early March 2007. For many of the Microsoft products affected by the 2007 daylight saving time change, the most recent versions will not require an update; however, earlier versions will. 

Depending on the particular product or scenario, these updates will be released through Microsoft Customer Support Services (CSS), hotfixes incorporated in Knowledge Base articles, Windows Update, Microsoft Update, Windows Server Update Services (WSUS), and the Microsoft Download Center. 

What users can do to ease the transition

• Include the time of the meeting in the e-mail request so that invitees can double check the correct meeting time (such as, "Project brainstorming - 11:00 A.M. Central Time").
• Exercise caution with the appointments and meetings in the extended DST period. When in doubt, verify the correct time with the organizer.
• Consider printing out your weekly calendars during the extended DST period prior to applying the Windows patch containing the updated time zone definitions and running the Outlook Time Zone Update tool so that you can keep track of which meetings were scheduled before and after you run the tool.