Comment Sometimes I hear a story that is simply breathtaking in its stupidity and potential for disaster. For your delectation, horror, and amazement, here is one relayed to me by a good friend a few days ago.

He's living in a European country that shall remain unnamed; in addition, the names and some details have been changed to protect the guilty (and the very dumb). It was transmitted to me via Skype, so I've also cleaned up the spelling and punctuation common to IM conversations so that it's more readable.

Boy have I got a story for your SecurityFocus column. My brother-in-law just bought a used Intel 20" iMac. The seller was a nice looking blonde, who didn't wipe the disk. You can probably see where this is going, but it's better than that. For some reason, he thought he needed her password to reinstall the system, so he called her and she gave it to him. Well, he had already seen some pornographic pictures on the hard drive that weren't password protected. Most of them weren't too explicit, aside from a couple of [oral sex] shots. But the password uncovered some videos where she gets sodomized, apparently by her boyfriend, or only one guy at any rate. Now the pics and vids are all on his iPod. He pulled them off the computer. It gets better.

At this point, I was thinking, "How in the world could it?" But my buddy was right. It got better.

My brother-in-law doesn't watch a lot of television, but somehow he figured out that the blonde is the host of [a very popular television show in that country]! I saw the vids and I went to the official website, and there she was. There's no doubt about it, it's the same woman. I couldn't believe it either. How can you be that stupid!?

Don't even bother asking me for her name, or the name of the TV show, as I've been sworn to secrecy. Instead, let's ponder the lessons we can learn from this salacious debacle.

Lesson 1: Wipe your disks

I've touched on this one before, and I know it seems like common sense to the folks reading this column, but my pal's story sure makes one thing painfully clear: many (most?) "ordinary" users don't understand the concepts of wiping a hard drive securely before relinquishing a computer.

It's one thing to drag your personal files to the trash and then empty it - lots of people undoubtedly think that will be enough to protect them. A few more knowledgeable ones understand that trashed files can still be recovered, so they want to remove that sensitive data more completely.

This usually means asking a friendly computer nerd for advice or help, or Googling for freeware, or paying for some commercial piece of software that will overwrite data the necessary number of times (Editor's note: Mac users can use the Secure Empty Trash menu to securely delete files). A tiny number of people - call them "paranoid security experts" - will go the final step and drill, bash, or bend their hard drives so that the data will be totally unrecoverable.

And then we have the...well, I don't really want to call them users, since they're more used by than users of their computers - people who don't even try to remove their data from the PCs in their possession. Even if that data is intensely personal. As in, involving acts or knowledge that really should be kept private.

Or, to put it another way, in what reality did that young woman think leaving pictures of her engaged in sexual acts on her Mac was a good idea? Did she not understand that those images and videos were left on the machine that she was selling? Had she copied them somewhere - to another machine, an iPod, or a USB stick - and thought that copying was actually moving?