Windows Defender Help

Check for New Definitions Warning

To ensure that your computing experience remains as secure as possible, Microsoft releases regular updates for Windows Defender definition files. These definitions files are basically a repository of all spyware and other potentially harmful and unwanted software that might infiltrate your system through external sources such as the Internet and external media, such as CD-ROMs, DVDs, and zip drives. Definition updates help you protect your computer against the latest spyware and other malicious software. These updates are delivered to user computer by using the Microsoft Windows Update, Automatic Updates, and Windows Server Update Service (WSUS) features.

Soon after you download and install Windows Defender on your Windows XP or Windows 2003 computer, the application searches for new updates on the Internet.

During the process, an error message similar to the one given below may be displayed on the screen:

Definitions allow Windows Defender to detect the latest harmful or unwanted software and prevent from running on your computer.

When this error message is displayed, the Check for updates now button might not be available. Moreover, if you start checking for updates by selecting the Check for Updates command from the Windows Defender Help menu, you may be informed that no updates are available.

Cause of the Error

This error occurs when the Windows Defender tool is unable to automatically download and update its definitions.

Resolution Steps

To fix this error and update the Windows Defender tool, you need to enable the Windows Automatic update feature. To do this, follow the steps listed below depending on your operating system.

Windows XP and Windows Server 2003

1. Open Start menu, select the Run command, type wuaucpl.cpl in the Open box, and then click the OK button.
2. Select the Automatic (Recommended) option.
3. (Optional) Specify the time you want your system to check for the updates.
4. Select the OK button to apply your changes and exit the Automatic Updates dialog box.

Windows Vista

1. Open Start menu, point to All Programs, and then select the Windows Update command.
2. Select the Change Settings link.
3. Next, select the Install updates automatically (recommended) option.
4. In the Recommended updates section, select the Include recommended updates when downloading, installing, or notifying me about updates check box, and then select the OK button.

Note: If prompted provide the administrative user name and password to the system.