Do you search or find programs to install, simply by using Google, and choosing any link available? Maybe you also don't read the windows that pop-up once installation begins. If both of those are true, you also are likely to skip the EUA (End User Agreement) that may also pop-up. If all the above are true, your computer is most likely running on borrowed time.
Hidden programs are in a vast majority of the otherwise useful application or game you're installing on your computer. These programs are known by many names: