When you perform a custom installation of Windows Defender on x64-based versions of Windows, Windows Defender does not work correctly

When you perform a custom installation of Microsoft Windows Defender or later versions on x64-based versions of Microsoft Windows, Windows Defender does not work correctly.

This problem occurs because some files are not installed in the correct location when you perform a custom installation of Windows Defender on x64-based versions of Windows.

To resolve this problem, uninstall Windows Defender, and then reinstall Windows Defender by using the default installation. To do this, follow these steps:

1. Click Start, click Run, type appwiz.cpl, and then click OK.
2. Click Window Defender, click Remove, and then follow the steps to remove the program.
3. Click Start, click Run, type cmd, and then click OK.
4. Type the following command at the command prompt, and then press ENTER:
   MsiExec.exe /x {A5CC2A09-E9D3-49EC-923D-03874BBD4C2C}
5. Click Yes.
6. Reinstall Windows Defender by using the default settings.

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

Technical support for x64-based versions of Microsoft Windows

If your hardware came with a Microsoft Windows x64 edition already installed, your hardware manufacturer provides technical support and assistance for the Windows x64 edition. In this case, your hardware manufacturer provides support because a Windows x64 edition was included with your hardware. Your hardware manufacturer might have customized the Windows x64 edition installation by using unique components. Unique components might include specific device drivers or might include optional settings to maximize the performance of the hardware. Microsoft will provide reasonable-effort assistance if you need technical help with a Windows x64 edition. However, you might have to contact your manufacturer directly. Your manufacturer is best qualified to support the software that your manufacturer installed on the hardware. If you purchased a Windows x64 edition such as a Microsoft Windows Server 2003 x64 edition separately, contact Microsoft for technical support.

For product information about Microsoft Windows XP Professional x64 Edition, visit the following Microsoft Web site: For product information about x64-based versions of Microsoft Windows Server 2003, visit the following Microsoft Web site: