Article ID: 935511 - View products that this article applies to.
When you try to start Windows Defender after you upgrade from Microsoft Windows XP to Windows Vista, you receive the following error message:
Application failed to initialize.
This problem may occur if you uninstall Windows Defender from the computer after you upgrade the operating system to Windows Vista.
Note If you receive the error message that is mentioned in the "Symptoms" sections but you have not uninstalled Windows Defender through Programs and Features, you may be receiving this error message because of a different issue. The steps in this article address only issues in which Windows Defender has been removed from the system.
To resolve this issue, use method 1. If method 1 does not resolve the issue, go to method 2.
Method 1: Use System Restore to restore Windows VistaUse System Restore to return Windows Vista to a restore point that was created before this issue occurred. To do this, follow these steps:
Method 2: Reinstall Windows VistaFor more information about how to perform an in-place upgrade of the Windows Vista operating system, click the following article number to view the article in the Microsoft Knowledge Base:
918884Follow the steps that are listed in the "Upgrade Procedure" section to perform an in-place upgrade of Windows Vista.
(http://support.microsoft.com/kb/918884/ )How to install Windows Vista
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Article ID: 935511 - Last Review: September 23, 2011 - Revision: 3.0