After Office 2007 SP2, Outlook takes a long time to close and Outlook.exe remains running in the background


After the release of Office 2007 Service Pack 2 (SP2) or the February 2009 cumulative updates (articles 961752 and 967688) for Outlook 2007, Outlook takes a long time to close (slow shutdown). While Outlook is closing, the Microsoft Office Outlook icon remains in the system tray, as shown in the following figure.

The screen shot for the Microsoft Office Outlook icon.

While this icon is displayed in the notification area of the Taskbar, the Outlook.exe process continues to run (as seen in Task Manager).

This is experienced by users who have .PST or .OST files in their profile.


This problem occurs when the following registry data exists on the workstation exhibiting the problem:

Key: HKEY_CURRENT_USER\Software\Microsoft\Office\x.0\Outlook\PST
Key: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\x.0\Outlook\PST

DWORD: PSTNullFreeOnClose
Value: 1

Note, x.0 in the above registry keys represents your Outlook version (15.0 = Outlook 2013, 14.0 = Outlook 2010, 12.0 = Outlook 2007)


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:

322756 How to back up and restore the registry in Windows

To resolve this problem, please make the following changes:

  1. Exit Outlook and wait for the Outlook.exe process to completely close.

  2. Start Registry Editor. 

    - In Windows 7 or Windows Vista, click Start  type regedit in the Start Search box, and then press ENTER.

    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 in the Open box, and then click OK .

  3. Locate and select the following registry key, where x.0 corresponds with your version of Outlook (14.0 = Outlook 2010, 12.0 = Outlook 2007)


    If you find PSTNullFreeOnClose under the \Policies hive in the registry, please check with your administrator to see if this setting is being pushed to your client through Group Policy. If it is being pushed through Group Policy, you will have to disable or remove the policy setting to update this data in the \Policies hive of the registry. 

  4.  Right-click PSTNullFreeOnClose, and then click Modify.

  5. In the Value data box, type 0 and then click OK.

  6. Exit Registry Editor.

More Information

The PSTNullFreeOnClose registry value is designed to force Outlook to overwrite deleted data when you close Outlook. However, the PSTNullFreeOnClose registry data does not work in Outlook 2007 or Outlook 2007 SP1. Therefore, the Outlook shutdown process in these earlier builds of Outlook 2007 is the same (does not overwrite deleted data), regardless of the value for PSTNullFreeOnClose. This problem is fixed in Office 2007 SP2 (and the February 2009 cumulative update). After you install SP2 and Outlook finds PSTNullFreeOnClose=1, the shutdown process is longer because the deleted data in your .pst or .ost file has to be overwritten. As this problem was fixed in Outlook 2007, the same resolution applies to later versions of Outlook.

For additional information on the PSTNullFreeOnClose registry value, please see the following article in the Microsoft Knowledge Base:

245776 OL2000: New Outlook 2000 Feature Removes Deleted Data from .pst and .ost Files;EN-US;245776


Id. de artículo: 2022995 - Última revisión: 09/03/2013 06:25:00 - Revisión: 12.0

Microsoft Outlook 2013, Microsoft Outlook 2010, Microsoft Office Outlook 2007

  • KB2022995