OL2000: 'Error in Registry for Extension Voice Enabled" Error Message When You Start Outlook 2000 (310416)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

When you start Outlook 2000, you may receive the following error message:

Error in registry for extension voice enabled. The format or syntax is invalid. Please reinstall Outlook. Outlook requires Exchange Extensions 4.0 or higher.

CAUSE

This behavior can occur if the HKEY_LOCAL_MACHINE\Software\Microsoft\Exchange\Client\Extensions registry key is not deleted after Extend.dat has been deleted. Extend.dat is a binary file that caches extension settings.

RESOLUTION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To resolve this behavior, delete the relevant registry key, and then delete the Extend.dat file:

Start Registry Editor (Regedt32.exe).
Locate the following key in the registry:
HKEY_LOCAL_MACHINE\Software\Microsoft\Exchange\Client\Extensions
Click the Extensions key, and then click Delete on the Edit menu.
Quit Registry Editor.
Delete the Extend.dat file, which is located in C:\Windows\Application Data\Microsoft\Outlook.