XPAntiVirus (also known as XP Anti Virus, XPAnti Virus and XP AntiVirus) is fake spyware removal tool that is usually downloaded onto your computer by a Trojan (most likely the Zlob Trojan) or under dubious circumstances without your consent. Once downloaded, XPAntiVirus begins to haunt the user by displaying false security alerts and "detecting" fake threats. The purpose is to get the user to purchase the full version of XPAntiVirus spyware removal application. (via)