Note To determine whether a computer is running a 32-bit version or a 64-bit version of Windows, click the following article number to view the article in the Microsoft Knowledge Base:
32-bit versions of WindowsTo download the Windows Defender definition update file for 32-bit (x86-based) versions of Windows, follow these steps:
- Click the following link: http://go.microsoft.com/fwlink/?linkid=70631
- In the download dialog box, click either Run or Save.
- Click Run to install the definition file immediately.
- Click Save to save the definition file to the computer. To install the saved definition update file, click Start, click Run, locate the folder where you saved the definition file, double-click the Mpas-fe.exe file, and then click OK.
- When the definition file runs, a file extraction dialog box appears. The dialog box indicates that the definition update is installing. After the file extraction dialog box closes, to verify that the Windows Defender definitions are updated, follow these steps:
- Start Windows Defender.
- Check the definition version that is listed in the box at the bottom of the Windows Defender Home dialog box.
Note To install the file on a computer that is running Windows Vista, right-click the file, and then click Run As Administrator to install it.
If you are a corporate customer, you should use Windows Server Update Services (WSUS) version 2.0 or later versions to distribute Windows Defender definition updates. However, you can also use a user logon script to manually install a definition update by running a Windows Defender definition update file.
The Windows Defender definition update file (Mpas-fe.exe) can use the -q command-line execution switch. This switch installs the definition update in quiet mode. Quiet mode suppresses the definition file extraction dialog box. For example, type the following command:
64-bit versions of WindowsIf you run a 64-bit version of Windows, download the Windows Defender Update Definition file by clicking one of the following links.
Note You must be running a 64-bit version of Windows to run a 64-bit version of Windows Defender. 64-bit versions of Windows include x64-based versions and Itanium-based versions.
To download the Windows Defender definition update file for x64-based versions of Windows, click the following link:
To download the Windows Defender definition update file for Itanium-based versions of Windows, click the following link:
Technical support for x64-based versions of Microsoft WindowsIf your hardware already has a Windows x64 edition 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 Windows Server 2003 x64 edition separately, contact Microsoft for technical support.
For product information about Windows XP Professional x64 Edition, go to the following Microsoft website: http://www.microsoft.com/windowsxp/64bit/default.mspx
For product information about x64-based versions of Windows Server 2003, go to the following Microsoft website: http://support.microsoft.com/windowsserver2003x64
For product information about Windows 7 64-bit versions, go to 32-bit and 64-bit Windows: frequently asked questions
Article ID: 923159 - Last Review: Jul 12, 2012 - Revision: 1