For many people, these may seem like reliable and trustworthy sources and sites, so they do not question whether or not a download should occur. This scan can lead a person to believe that there are issues with their existing system, or there may be if they do not perform this task. But every once in a while, there may be an ad that appears indicating that a download is necessary to scan the system. This is the time it runs the fastest, the smoothest and is untouched by terrible things like a virus. Everyone knows that starting with a fresh computer is the best part of having a system.