Your anti-virus program should be configured to check for updates at least once each day. If you are a high-risk Internet user (that is, if you have a propensity to open spam messages or you surf a lot of “grey” sites), you should check several times per day.
Your anti-virus program should be configured to scan your entire hard drive for viruses at least once per week. Because a virus scan can make other programs run more slowly, you can configure your anti-virus program to scan your computer when you aren’t using it – at night or during your lunch break, for instance. If you use external hard drives or thumb drives, it’s a good idea to scan those for viruses too.
Heuristics Turned On
Anti-virus programs catch viruses in two ways: by recognizing their “signature”, and by recognizing their behavior. The latter type of detection is known as “heuristics”. Make sure your anti-virus program has this turned on.