Check for Updates
1. Restart your computer.
2. Click 'Start,' 'All Programs' and 'Windows Defender.'

3. Click the 'Check for Updates Now' button.
4. Download any updates provided. Proceed with the next section if you continue to receive error messages.
Manually Update Windows Defender
5. Restart your computer.
6. Visit the Microsoft Malware Protection Center. See Resources.
7. Download the latest updates for your type of operating system (32-bit or 64-bit). Save the file to your desktop or to your downloads folder.
8. Close your browser, and double-click the definition file you downloaded. Follow the on-screen prompts to complete the installation.
Update Windows
9. Click 'Start,' 'All Programs' and 'Windows Update.'
10. Click 'Check for updates.'
11. Select and download any critical or important updates.
12. Follow the on-screen prompts to complete the update process. Restart the computer if prompted.
Rename the Software Distribution Folder
13. Close all programs.
14. Click 'Start,' then 'Run.' Type 'cmd' (without quotes), and press 'Enter.'
15. Type the following lines in the command prompt box. Press 'Enter' after typing each line.net stop wuauservnet stop bitsren %systemroot%\SoftwareDistribution SoftwareDistribution.oldnet start wuauservnet start bits
16. Close the command prompt box.