Computers, I'm convinced, must be related to house cats. Just when you think that everything is purring along nicely, a computer can stick its claws right into your heart.

One moment, it's a computer; the next, it's a big paperweight. That shocking instant — when you hit the power switch and nothing happens — triggers a fine cloud of panic that turns even the most rational person into a wild-eyed fixing machine.

Today, while we are both calm, let's map out a game plan for that inevitable day. Stick this column in a desk drawer so it can help you calm down and avoid making things worse.

At the risk of sounding like a Zen master, first do nothing. Almost anything you do in the first moments is likely to be wrong. Calmly jot down any symptoms that occurred in the days before the computer died, as well as what you were doing at the time. You may find a clue there.

Now that you've had time to let the panic settle, check the most obvious causes. And, yes, that starts with checking to see that the power cord connections are sound. Then check to make sure that the surge protector or UPS is turned on and plugged in.

Some surge protectors and power strips can automatically switch off if electricity to your home is interrupted. Plug a small lamp or other AC device into the power outlet that you're using to make sure a circuit breaker hasn't popped.

Next look at the front panel of your computer. Are any lights on? If not, the power supply may have gone bad. It's an easy replacement — most large computer stores offer them — but many will be leery of that repair. Those of you who are competent to do it probably know it and those who aren't know it, too (I hope).

But what if the front panel lights are on but the machine won't do anything? Let's turn it off and see what it can say for itself. Hit the power switch and restart.

Do you see an on-screen message when the computer restarts? For instance, if the hard disk has failed, you'll see a message. But that's not the only way that a computer can tell you its woes. Most use beeping sounds to alert you to problems. The meanings of these codes vary according to the kind of motherboard installed in the computer. Your manual will tell you the type of motherboard installed, or you can use another computer to check the manufacturer's Web site. Once you know the brand of motherboard, you can use this site to decipher the beeps: http://www.computerhope.com/beep.htm

Of course, the computer may be mute: No on-screen messages, no beeps. If so, try disconnecting any unneeded accessories — printers, scanners, etc. — and turn the machine on again. At times, a malfunctioning device will cause the problem and, if not, you can at least rule it out.

The next step is to open the case.

Some of you will be reluctant. That's fine. There's nothing wrong with packing up the computer and taking it to a repair shop at this point.

But if you proceed, take a look at the cables and connectors inside once you have the case open.

Are they firmly seated? Now — using the manual or just your knowledge — locate the processor chip. Most often, it will have a tiny fan connected for cooling. Is the fan turning?

Most computers will shut down if they overheat — a good thing. It's also a good idea to check the larger fan — usually at the rear of the computer — that cools the entire innards of the machine.

If there's nothing obviously wrong and the fans work, then try removing and reseating accessory cards.

Important: Shut down the power first.

OK. We've reached a fork in the road. This may be all you can do. But if you have spare accessory cards (like the video card, sound card, etc.), you can try removing the card that's in your computer and replacing it with one that you know is in working condition.

If the problem still isn't fixed, it's time to call it a day — and call for an appointment at a repair service.

Since you're reading all this with a computer that's working just fine, you can use these tips to prepare for the inevitable.

Make sure that you have the manual that came with your computer or download one and print it out. Also, it's a good idea to accumulate spare parts. Oftentimes, the problems aren't as dire as a computer that won't start at all. Many times, all you need is a replacement keyboard, video card, even a monitor or a mouse.

Next time your computer turns into a house cat, you'll have a better chance of avoiding those painful claws.

— Bill Husted writes for the Atlanta Journal-Constitution. E-mail: bhusted@ajc.com.