288 Chapter 11 TROUBLESHOOTING area of suspicion at a time. This means you have two approaches depending on the nature of the problem. In the case of a loss of video, you could use a subtractive procedure of checking one area before moving on to the next, such as replacing a problem- atic cable or trying another setting (like trying different video monitor inputs). Eliminate a potential failure point, and move on to the next. Or you may want a more additive approach where you discon- nect everything attached to the computer and add them back one at a time. This additive method would apply to problems with drives, networks, and other peripherals. It is also useful if you can't boot the system at all. Attach a peripheral and reboot. If successful, then add another peripheral and reboot again. If changing something doesn't fix the problem, then go back to the original state before you move on--there is no need to complicate the search by eating the breadcrumbs back to where you started. Keep track of every piece of software that is added to the sys- tem and when it was added. If someone has added software that loaded a driver (or another innocent piece of secret software) and