In August 2005, the United States Congress passed the Energy Policy Act, which changes the start and end of Daylight Saving Time (DST) as observed in the United States. Some additional countries/regions are following the U.S. change. As a result, 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 dates are referred to as the extended DST period.

All systems depend on international timekeeping standard
Outlook calendar and system times will be affected.

Unless certain updates are applied to each of your servers, workstations and mobile devices, it is likely that the time zone settings for the respective system clocks may be incorrect during this four week period. When your time zone settings are incorrect, your clock may be off by one hour, and certain applications running on your Windows-based devices, computers and servers may not display the correct time (i.e. Outlook appointments, etc). To address this, Microsoft is providing many free updates and tools that will update your system automatically. While the change in daylight saving time applies to the U.S. and Canada, the change may impact customers based outside North America.