Antivirus protection and how to avoid viruses
Is your computer running more slowly than usual? Does it stop responding, freeze often, or display other odd behavior? It might have a virus. Fortunately, if you update your computer regularly and use antivirus software, you can help permanently remove unwanted software and prevent it from being installed in the first place.
Windows Defender (built in to Windows 8), Microsoft Security Essentials, and other antivirus software programs download the latest updates over the Internet to fight new malware. Windows Defender Offline helps protect against advanced malware that can't always be detected by antivirus software.