Running a virus scan on your computer with outdated definitions is essentially as useful as not running a virus scan at all. Virus definitions contain information that allows your computer to identify and remove all of the latest viruses from your computer. If your definitions are out of date the program will miss newer viruses which will leave your computer vulnerable to attack even if the results of the scan come up clean. If you’re using Microsoft’s free “Security Essentials” anti-virus suite, you can update your virus definitions in just a few seconds by following the right steps.
Click the “Start” button on your desktop. In the box that appears, type “Security Essentials” into the “Search” box. The first search result will be the icon for the Microsoft Security Essentials program. Click the icon to open the program.
Look at the “Virus and spyware definitions” listing in the main window on screen. Next to this will be a term that specifies whether or not your virus and spyware definitions are up to date. If the phrase “Up to date” appears next to this listing there is no need to update your definitions. If anything else is written next to this listing, continue to “Step 3.”
Click “Update.” The box on screen will give you a detailed breakdown of exactly how recent your virus and spyware definitions are. You can check when the definitions were created, when they were downloaded and what version number your currently installed definitions actually are. This will give you some indication of how many viruses your computer could be missing in each scan with out of date definitions.
Click the gray “Update” button. Microsoft Security Essentials will search for available updates for your virus and spyware definitions. It will then automatically install the updates onto your computer. No restart of the program or your computer is necessary after this process is finished. Wait for the status of your definitions to change to “Up to date” before continuing.
Click the “Home” tab at the top of the window. Click the “Full” box on the right side of the screen followed by the “Scan Now” button. This will immediately perform a full scan of your computer using the updated definitions. This process will make sure that any viruses that were missed in previous scans are located and removed.