This morning, as I went about my merry business on my computer, I had an e-mail come in from an old college friend through Facebook.

I guess I should have known. I think of myself as pretty savvy, never opening strange attachments, avoiding clicking on links that look suspicious and so on. But since this came from a friend through Facebook, I let down my guard. I read the e-mail, rolled my eyes, but clicked on the link, anyway.

Seconds later, my computer security software told me that my PC had been attacked -- but the virus that tried to leech onto my hard drive had been stopped.

I e-mailed my friend and confirmed that he hadn't sent me the e-mail, and he said that his work computer was apparently infected by some sort of virus.Turns out, I later learned, this virus is called the Koobface virus.

The e-mail I received reads (and I apologize for its language):

Todd sent you a message. (In this case, Todd is this particular friend of mine.)

Subject: Yourr ass got ccaught by our speecial spy camera!!

"WOW
Here's where the link was. I'm not actually putting the real link here for obvious reasons.

Now looking at this, sure, I was an idiot for clicking on the link. But, you know how it is -- you're working a mile a minute, you're clicking on stories here and there. I didn't even notice the spelling errors. I thought it was a crude e-mail of my friend to send, but remembering how he used to drink at some college parties, his writing this e-mail didn't seem like that much of a stretch.

Of course, this is almost 20 years later, but that's the memory I suddenly had of him, and in the two seconds that my brain processed the receiving of this e-mail, everything seemed logical.

So I clicked on the link and am now extremely relieved that, years ago, I began protecting my computer with security software protection.

Anyway, since a computer virus can potentially harvest your passwords and drain your bank account, and certainly cost you plenty of time and money in trying to rid your PC of unwanted malware and other digital evil, I just wanted to warn everyone.

If somehow you're not protected, this web site has a pretty thorough explanation of where to find computer protection, for both Windows and Mac users. And though I don't consider myself an expert on the topic of computer security, I can personally recommend Norton from Symantec and Webroot. I've used both and have been pretty pleased.

In any case, if you get an e-mail like the one I just described, hit delete. Sure my warning is pretty obvious by now. But no matter how smart you might think you are, you just may forget.

Geoff Williams is a freelance journalist and the author of C.C. Pyle's Amazing Foot Race: The True Story of the 1928 Coast-to-Coast Run Across America (Rodale).