The Hassle: My PC overheats (the motherboard monitor beeps) toward the end of the evening, even though my home-office temperature is cool.

The Fix(es): I'll lay odds that your computer's case is full of dirt, dust, and other crud. If you have a pet, the system is likely to be loaded with hair, too. Another bet: Your PC sits on the floor, under your desk, gathering dust. Here's what to do.

Before opening the case, unplug everything--power cord, phone line, cable modem, and ethernet cables. After opening the case, touch the power supply to discharge any static and to ensure that you and the inside of your PC are at the same voltage. (Repeat this process every time you touch the PC's innards.)

Start by removing the foam filters, if your PC has any, on the fan vents. Gently clean the filters in a mild solution of dish soap and cool water, and let them dry before putting them back into place. (Better still: Buy a foam air-conditioner filter, cut it to size, and replace all of the filters.)

Remove large clots of dust by vacuuming the fan vents from the outside of the case. However, be very cautious about vacuuming inside the case. Don't touch the motherboard or any add-in cards. At most, just suck away the dust that is lying on the base of your tower and on the bottoms of the system's empty drive bays. And avoid using brushes on components.

Alternatively, if the weather is dry and not too cold, carry the PC outdoors, and bring along a can of compressed air. I bought a can that had a foot-long hose attached; you can also buy tubing at a hobby store. The hose is perfect for clearing away dust throughout the case. It lets you hold the air can upright, as well; spraying the can at a tilt causes a wasteful blast of icy liquid propellant, and the resulting temperature change can damage components.

You may be tempted to spin the fan blades of the CPU's heat sink with a gust of air to clean them, but don't. The fan can't take the high rpm's. I know--I ruined one. Your best bet is to hold the fan and then blow with the air. Next, use a cotton swab with a weak alcohol solution to finish cleaning each blade. Carefully blowing the dust from between the blades of the heat sinks is even more important than cleaning the fan. Place the nozzle between the fan blades and along the open sides of the heat sink until no more dust flies out. Do not use an air compressor (like the kind you use to fill your tires at a gas station)--they often contain a mix of oil and water.

Finally, put your PC on rollers. Raising your computer off the floor, even just 6 inches, will reduce the amount of dust that gets sucked into the fan vents. I use a small furniture dolly, available at hardware and home appliance stores.