How to Run a Full System Scanby Andrew Meer
To protect your computer from malware, Windows 8.1 features a built-in anti-virus applet called Windows Defender that scans for infected files or applications. In addition to a quick-scan option, Windows Defender also provides a full-scan option that scans your computer more thoroughly, though the time it takes to complete a full scan can exceed an hour, according to Microsoft. Before running a full scan of your computer, however, check that Windows Defender has the latest virus definitions installed.
Using Windows Defender
From the Start screen, type “Windows Defender” (without quotes), then press “Enter” to open the Windows Defender application. Click the “Home” tab, then check the status next to “Virus and Spyware Definitions.” If it displays “Out of Date,” click the “Update” button to automatically install the latest malware definitions. After updating, click the radio button next to “Full” under the “Scan Options” section and then click “Scan Now." Once Windows Defender finishes scanning your computer for viruses, it reports viruses it found (if any) and the action it took on infected files.
Using Third-Party Scanners
If you prefer using third-party malware scanners instead of Windows Defender, alternatives exist such as Norton, Kasperky and McAfee that cost a fee, and you can also try free scanners such as Avira, Avast and Malwarebytes. All these applications feature full-scan modes that thoroughly scan your computer for malware.