A Harvard administrator turns on her computer, only to find the cryptic message "Invalid System Disk" on her screen as the computer refuses to start. The hard drive contains the only copies of five years' worth of documents, databases and recommendations. Luckily, the virus that infected her computer could be removed--this time.

An undergraduate has most of her room wiped out in a fire. Miraculously, her Macintosh escaped without damage, but the blaze destroyed a decade's writing. If the computer had been damaged, some of her documents would have been irretrievable.

These aren't just hypothetical situations. These events happened over the span of the last two weeks, and countless more disasters happen like them every day. In these two cases, the computer's owners were very lucky that none of their data was lost or damaged.

But it's not worth taking unnecessary chances with data. At any academic institution, the preservation of intellectual property is not just desirable, it's your academic or professional career on the line. After all, what if the STONED virus had infected John Locke's disk and eaten up his Second Treatise before he published it? What would the world be like if Newton's Principia had been the victim of a hard disk head crash?

Whether or not you think your Ec problem set will have the staying power of an intellectual masterpiece, it can be a real hassle to have to start a paper all over again because your computer ate it. And for faculty members, the words they write really are their lives' works, for better or for worse.

The quick and easy solution is backing up data--saving a second or third copy of your documents and keeping the copy somewhere safe.

Like voting, the best rule of thumb is to back up your data early and often. But like voting, people tend not to make copies of their data as much as they ought to.

The cheapest way of backing up your data is simply to save all of your documents in two places: on your hard disk and onto a floppy disk. That way, if something should happen to one copy, you have another waiting for you.

Unfortunately, floppies have problems of their own. For one thing, they aren't very durable or reliable. On average, most floppy disks will fail within a few years of life if used often enough. Floppies also hold only a megabyte or so of data, so you can forget storing your multimedia assignment on one--although Zip or EZFlyer drives can be a good solution if you have large files for casual backup.

And remember that if you're not careful, backing up on floppies won't help you in case of theft. A criminal will steal the computer and everything near it--including those backup floppies you thoughtfully made. Goodbye, data.

A better solution for protecting your data is to purchase a dedicated tape back-up drive for you Mac or PC, which can store the entire contents of your hard disk. These drives install easily into your computer or plug into the back of it. They use special tapes to store from 120 Mb or two gigabytes worth of files.

The tape back-ups provide the advantage of allowing you to make back-ups at any time of the day, even while you're away from the computer--a big help for the forgetful or the lazy. A good tape drive is available for around $150 at any computer store.

Whatever method you choose, though, pick a way of backing up your data and then stick to it. The only person you'll be helping is yourself in the long run.

--Kevin S. Davis is director of HASCS's Advanced Support Team and an independent computer consultant. His e-mail address is ksdavis@fas.harvard. edu.