Effects of spyware. A piece of spyware rarely "lives" alone: an affected computer can rapidly become infected with large numbers of spyware components. Users frequently notice unwanted behavior and degradation of system performance. A spyware infestation can create significant unwanted CPU activity, disk usage, and network traffic which thereby slows down legitimate uses of these resources. Stability issues, such as application or system-wide crashes, are also common. Spyware which interferes with networking software commonly causes difficulty connecting to the Internet. In some cases of spyware infection, the user has no awareness of spyware and assumes that the system performance, stability, and/or connectivity issues relate to hardware, to Microsoft Windows installation problems, or to a virus. Some owners of badly infected systems resort to contacting technical support experts, or even buying an entire new computer system because the existing system "has become too slow." Badly infected systems may require a clean reinstall of all their software in order to restore the system to working order. This can become a time-consuming task, even for experienced users. Only rarely does a single piece of software render a computer unusable. Rather, a computer rarely has only one infection. As the 2004 AOL study noted, if a computer has any spyware at all, it typically has dozens of different pieces installed. The cumulative effect, and the interactions between spyware components, typically cause the stereotypical symptoms reported by users: a computer which slows to a crawl, overwhelmed by the many parasitic processes running on it. Moreover,