Just as I was about to turn off my personal computer the other night, it occurred to me that it had been quite a while since I'd last made a backup copy of the disk with my financial records.

So, fired with good intentions, I told the computer what to do, slid the irreplaceable disk, which contained every check and charge entry since January, into the disk drive -- and then watched in horror as my machine fiendishly left the records of my admittedly paltry financial empire in electronic tatters.

I haven't the faintest idea what I did wrong (although I immediately realized what I could have done to prevent it), but I can assure you that the warning is clear: When disaster strikes on a personal computer, it is going to be devastatingly swift, complete and unexpected.

It'll come as no surprise to anyone that, like just about everything else designed to make life easier, the personal computer has an equally great potential for disrupting your life.

Take what happened to me. On the one hand, the computer made my home financial management more precise and analytical. On the other, it exposed my records to hazards they never faced before when they were simply kept in a checkbook.

Human nature being what it is, it would be easy for me to blame the computer for my current financial confusion. After all, we've all been taught that it's always the computer that's the culprit when you find your water bill for June (the month you were away on vacation) to be $21,211.88.

But the simple truth is that the vast majority of those so-called "computer errors" are directly attributable to human beings -- people like the government clerk who incorrectly entered your water meter reading into the computer as well as people like me who lose their financial records in a blinding moment of confusion.

There is a moral to all this, but it's not that a personal computer is more hazardous to your mental health than it's worth. Quite the opposite. If you take your time and plan properly, thereby cutting your "exposure" down to near zero, you'll find that you really can do all those things with a computer that you have heard about -- such as keeping your home financial records.

In my case, I could have taken a simple step that would have protected my disk from any accidental effort on the part of the computer to record on it. All that was needed was a tiny strip of tape placed over a notch in one edge of the disk, which would have made it impossible for the computer to record anything on it.

There are other things of a preventive nature that you can do to safeguard not only your precious records but your equipment as well. When you consider that the typical home computer system is now worth about $2,500, it's foolish not to take certain precautions.

Make copies of everything. If you have a printer, print out copies and save them. I did, so really I lost only the ability to juggle eight months' worth of figures in the computer's memory rather than in mine.

Disks and tapes -- the most common media for saving information gleaned from home computer systems -- are fragile. Treat them with respect. Do not touch exposed surfaces. Do not expose them to temperature extremes. Store them in a safe place. The information stored on them is preserved magnetically, so keep them away from sources of magnetism.

Buy a voltage regulator. It "filters" the electricity that goes into your system, protecting it against power surges that, even in short bursts, can damage or shorten the life of your system. They cost about $15 and up. Some even contain batteries that keep your computer going if there's a power outage.

Remember, too, that every time you plug something new into the guts of your computer -- like additional memory capacity or the paraphernalia you need to get a printer to cooperate with your system -- your machine draws more electricity, and that means more heat. Couple that with less room inside for air to circulate andyou run the risk of accelerated deterioration of parts because of excessive heat.

Solution: buy an add-on fan that gently sucks air through the heart of the computer, cooling it off.

In the end, the extra precautions are all common sense, like reading your manuals and program instructions, and keeping all food and drink far away from the terminal, and spending a few dollars for prevention's sake.

And they're well worth it.