How to manually download the latest definition updates for Windows Defender
32-bit versions of Windows
To download the Windows Defender definition update file for 32-bit (x86-based) versions of Windows, click the following link:
http://go.microsoft.com/fwlink/?linkid=70631 (http://go.microsoft.com/fwlink/?linkid=70631)
After you click this link, click Run to install the definition file immediately, or click Save to save the definition file to the computer. If you click Save, remember the folder where you save the file.
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.