When your computer is behaving strangely and applications are taking longer to load, software is running slowly, or the hard disk becomes non-responsive, it indicates that your system may be infected with malicious programs. In such a scenario, it is recommended to install AVG antivirus on your system. You can install any antivirus on your system, provided that you have purchased a genuine copy. However, AVG Free Edition is completely free to download and use, which makes AVG Free a popular option.