If your computer starts to behave strangely or displays any of the symptoms listed below, you may have spyware or other unwanted software installed on your computer.

• I see pop-up advertisements all the time. Some unwanted software will bombard you with pop-up ads that aren't related to a particular Web site you're visiting. These ads are often for adult or other Web sites you may find objectionable. If you see pop-up ads as soon as you turn on your computer or when you're not even browsing the Web, you may have spyware or other unwanted software on your computer.

• My settings have changed and I can't change them back to the way they were. Some unwanted software has the ability to change your home page or search page settings. This means that the page that opens first when you start your Internet browser or the page that appears when you select "search" may be pages that you do not recognize. Even if you know how to adjust these settings, you may find that they revert back every time you restart your computer.

• My Web browser contains additional components that I don't remember downloading. Spyware and other unwanted software can add additional toolbars to your Web browser that you don't want or need. Even if you know how to remove these toolbars, they may return each time you restart your computer.

• My computer seems sluggish. Spyware and other unwanted software are not necessarily designed to be efficient. The resources these programs use to track your activities and deliver advertisements can slow down your computer and errors in the software can make your computer crash. If you notice a sudden increase in the number of times a certain program crashes, or if your computer is slower than normal at performing routine tasks, you may have spyware or other unwanted software on your machine.