Shareware may or may not be limited - meaning that some functions may not be available to you until the program is paid for. These limitations are often small and don't interfere with the way its full version operations. They're really just implemented as a way to prompt payment. Remember that shareware is not freeware. And that would be an instant recipe for failure. Also be careful about installing operating systems that are incompatible with existing hardware. The hardware of Macintosh computers is extremely different from the hardware of Windows computers and under no circumstances will a Windows operating system work on a Macintosh machine! Perhaps we could make an effort to educate the people who want put viruses into the public about ways to display dissatisfaction with a service or product that don't involve harming innocent parties. In doing so, we just might reduce the number of virus news stories and protect our own investments at the same time. The following list defines some of the most common extensions that you'll find on your computer. .au - This extension indicates a sound file. Most sound players will load up and play this kind of file. .art - This extension indicates an image file that was compressed with AOL (America Online) technology. They "operate" whenever there's a conflict among commands. Remember that computers essentially run off of a series of commands and it's usually a smooth process. 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. It's funny, but people seem to forget that every computer and every program installed on a computer comes with its own help file. Even the operating system of a computer has a help file and it really should be the first place to look for answers. Help files are designed not only to guide the usage of a computer, they're also designed to solve problems.