Computers are great when they operate properly. Unfortunately, many things can go wrong with them. There are things every computer owner can do to prevent problems and to keep them operating reliably. To prevent damage to the computer's circuitry, always wait 20 seconds after turn the power off before turning back on; never turn off or reboot a computer while a disk drive light is on--this can destroy data; if the computer fails to start successfully when the power is turned on, turn the power off and check all cable connections, then restart the computer; always unplug a computer before cleaning it and use only a damp cloth when cleaning a computer or keyboard--never spray anything directly on the computer; never place a computer or monitor on an unstable surface; never place a computer near a radiator or heater; do not restrict air flow through the computer cabinet; do not use a computer in a built-in installation without adequate ventilation; never insert objects into cabinet slots; use only the type of power source recommended on the computer's label; connect all equipment to properly grounded outlets; store disks properly; and back up important data daily.