Deletion programs will analyze a computer's operating system and installed programs to determine which files are crucial to computer function versus which files are safe to delete. You already have such a program on your computer and it's Windows' Add/Remove Programs (available from the Control Panel). The commands in a program are pretty useless unless they have some data to act on so programmers either give the programs some data to work with (list of names or numbers for example) or they make the program generate it's own data. Sometimes, the data comes from an outside source like the Internet or the computer that the program runs on. But when one command conflicts with another command - or when one command asks for a process or information that isn't available, the computer returns results that aren't useable. That's an error. A prime example of this kind of error is when users attempt to use software that isn't applicable for their system. If these things aren't saved onto a computer, there's nothing critical to worry about other than restoring your computer to a non-virus condition. 3. Don't open files without scanning them with an anti-virus/anti-spyware program. In the past, the warning was to avoid opening files from people that you don't know. This is because the computer is a mere platform - a blank canvas, if you will - waiting for you to direct its operation or paint the picture of the perfect machine. All this is possible from making just a few changes in your computer's current configuration. Your computer's main configurations are housed in Windows Control Panel. The buttons on these main menus of course take you to additional menus, which in turn give you even more choices to make. And all of those choices will eventually bring you to the service that you need. One very important choice you'll want to keep your eye on is the option to return to the main menu.