The duration of an appointment changes from one hour to two hours unexpectedly when the appointment occurs at the same time as the DST transition

In Microsoft Office Outlook 2003, you create an appointment that is one hour long and whose end time is 1:00 A.M. on the transition day from DST to Standard time. Then, you change the time zone setting. For example, you change the time zone from Brasilia to Greenland. In this case, the appointment unexpectedly becomes two hours long.

This problem can also occur if you receive a meeting request for a meeting that ends at 1:00 A.M. on the transition day from DST to Standard time, and the meeting organizer is in a different time zone from you. For example, the meeting organizer is in the Brasilia time zone, and you are in the Greenland time zone.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
To resolve this problem, install the Outlook 2003 hotfix package that is dated February 24, 2009, and then set the EnableRecurDSTTransform registry entry to enable the hotfix package. To do this, follow these steps:

1. Install the Outlook 2003 hotfix package that is dated February 24, 2009. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
   965495  (http://support.microsoft.com/kb/965495/ ) Description of the Outlook 2003 hotfix package (Outlook.msp): February 24, 2009
2. Set the EnableRecurDSTTransform registry entry. To do this, follow these steps:
   1. Start Registry Editor.
      • In Windows Vista, click Start
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        , type regedit in the Start Search box, and then press ENTER.
        
        
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        If you are prompted for an administrator password or for confirmation, type the password, or provide confirmation.
      • In Windows XP, click Start, click Run, type regedit, and then click OK.
   2. Locate and then click the following registry subkey:
      HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Preferences
   3. On the Edit menu, point to New, and then click DWORD Value.
   4. Type EnableRecurDSTTransform, and then press ENTER:
   5. Right-click EnableRecurDSTTransform, and then click Modify.
   6. In the Value data box, type 1, and then click OK.
   7. On the File menu, click Exit to exit Registry Editor.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.