None of us would let a stranger into the house to rummage through our personal files. But that's exactly what lots of people do every year when they sell or give away their old computer.
CBS News Consumer Correspondent Herb Weisbaum has an important warning about this potential privacy problem and how you can protect yourself.
Millions of home computers are retired every year to be replaced by newer and better models. Getting rid of a computer is not like parting with any other old appliance. And, unless you take the proper precautions, its memory will linger on long after it's gone.
Just think of all the personal information in your personal computer - stuff that's nobody else's business. Over the years, your computer's memory can soak up an awful lot, from work projects and personal finances to love letters and more.
And as obsolete computers are retired, that information often goes with them, sometimes safely to the grave. But other discarded computers live on, donated to schools that need them for teaching or sold to thrift stores and flea markets where anybody can buy them.
"Those hard drives on those computers are like enormous tape recording devices," says Joan Feldman of Seattle's Computer Forensics. "They can contain volumes of information, some of it sensitive or confidential, that they wouldn't want anyone else to see."
Feldman's business is other people's business. Her company, Computer Forensics, recovers computer information needed as evidence in legal cases. She thinks people are too careless when they sell or donate an old computer.
Neal McManus bought a used computer and learned plenty about its previous owner. "Their bank accounts, their investments, their financial lives are in these files," he says.
Was his discovery a fluke?
By thrift store shopping, CBS News picked up a couple of used computers for less than $15 apiece.
Computer Forensics expert Shawn Howell thought an old Compaq 386 looked promising, so he booted it up. Almost immediately, he struck gold: Visa Gold.
He found payment information, what was paid in interest, that type of information and lots more, including personal information about two people named Bert and Lisa.
Bert and Lisa Flynn donated their old computer to charity less than two weeks ago as part of moving to a new home.
The Flynns were amazed at what CBS News found, which included their wedding list and his resume. They were glad it was CBS News that found them.
Someone running up some credit card bills literally could have stopped the closing on the Flynns' house.
"And it's also kind of scary when you know that someone has all your personal information, your family information with addresses and all that kind of stuff and even resumes. They know too much about you pretty much," says Lisa Flynn.
So what should you do when you say good-bye to that old computer?
"The best wy, we think, to really thoroughly destroy a hard drive is [to] drill a hole through it and make it unreadable," Feldman says.
This technique Feldman clearly enjoys demonstrating.
"By putting a hole in it, it can't spin. And you can't read it, and you can't get data off of it," she says.
Feldman explains one more tip: Simply deleting files does not work. Deleted files aren't really gone. They're just hidden, and it's not that difficult for somebody who knows what they are doing to resurrect them.
This is not just a problem for home computers. A number of businesses have been burned, by throwing away old computers that had their hard drives packed with private files.
If you don't want to drill through your hard drive, there are some software programs that will wipe the drive so clean it can't be read by anyone. Some that are said to do that can be found at Fat-Free Software's Web site, which offers Cover Your Tracks, and Isis Software's Web site, which offers Shiva Destroyer of Files.
To find an organization that wants your old computer, turn to a directory with national, state as well as international listings. Check out the PEP National Directory of Computer Recycling Programs Web site.