Your IT department always has your best interests in mind, right? Not always. Sometimes IT spreads disinformation, purposely or not. Regardless, you need to know the truth.

I'm in IT, so I'm going to share with you the top four IT myths I think you should know about. Here's what you need to know to see through the fear, uncertainty, and doubt some IT departments spread. Today, I'm talking viruses.

MYTH ONE: This is a common one. IT tells you it's your fault when your work PC gets a virus.

Nope! True, IT issued you a virus-free PC. And maybe you did some bone-headed netsurfing and ended up with a Trojan or a worm or some other nefarious malware. When you call your helpdesk, IT will have a little talk with you. Visit only reputable websites, the security admin will say. You might blush.

But wait. What's reputable, really? Is The New York Times a reputable site, in your view? You'd think so. But then this happened: In 2009, a so-called "unauthorized advertiser" at the NYT started selling fake antivirus software through the paper, after a tweet warning readers of a potential infection.

The NYT sent readers to a fake antivirus site to buy "software" to fix it. Spyware. You think? It was 2009, but it'll take a long time for the NYT to live that one down in my eyes.

MYTH TWO: As long as you don't download something or open a word attachment from an unknown source, your PC will be just fine.

Let's say you visit a site and a pop-up asks if you want to install a desktop weather app. You're smart enough to just say no. But sometimes, clicking both No and Yes have the same effect -- allowing the installation of the virus, spyware or trojan. Result: Infected PC.

IT rarely admits that it's possible to get a virus through a PDF file. Adobe allows third-party software installation, did you know that? So here, you can run into the same problem -- the software gives you the yes/no trick and invokes the virus. This happened at Twitter. Mousing over some infected text redirected tweeters to porn sites.

At this points, all bets are off. And when your spouse asks you why all that porn is on your business PC, now you know where you got it. At work!

MYTH THREE: IT gave you a virus-free workstation, so anything wrong with it is your problem now.

IT departments distribute pre-infected PCs from time to time. I've seen it happen.

Recently my AV server shot me an email saying that a PC had a virus and the AV client software quarantined it. Half an hour later, I got the same notice from the same PC for the same virus -- saying the AV software killed again. Half an hour later, same message.

I re-imaged the thing in place -- meaning I wiped the OS, its applications, and all the data, and installed a fresh image using Symantec Ghost.

I put it back in service; that is, I returned it to the user. But a half hour later, the same infected message popped up. This thing was sticking like malaria.

I wondered: Was her PC re-infected because she surfed to the same bad site? Unlikely. So I re-imaged it a second time and the virus returned again. Finally, I took the PC back into the lab, re-imaged it again and logged in as a test user. This time, I didn't launch a browser even. And sure enough, the AV server shot back the same infected notice.

So the virus was not in the OS, this I knew by now. But where was it? I ran Microsoft's new rootkit. It found nothing. I'd heard viruses can attach to network or video cards, but I checked and it wasn't that.

Finally, I just deleted the primary partition. And that did the trick. The virus, finally, was gone.

Now: when IT recycles and reissues a computer, it almost never rebuilds or wipes partitions. In this case, I had the advantage of the server's software spotting and quarantining the virus. But what if your IT department doesn't work that hard? And that brings me to the final issue.

MYTH FOUR: IT says your antivirus software is up-to-date, so you're safe.

As if. Every time an antivirus software maker creates a new update for its wares, virus writers take it up as a challenge. It's a cat and rat game but, in this case, the rats know when the cat can't give chase. And the rats -- and there are far more rats than cats here -- are winning.

So, when your antivirus software tells you your PC is free of viruses, know it means it's free of the ones it knows about. There are thousands out there it has no clue about. And more are written every day.

There are viruses you see and the fake viruses, like the fake antivirus software I mentioned, that trick you into thinking you've got a virus and charge you $49 to fix it.

Fortunately, you now know about fake antivirus software viruses -- and they comprise only about a fifth of the viruses on the web. The other 80 percent are the ones you don't see.

Such viruses steal credit card data and passwords; log keystrokes; attach themselves to secure browser sessions; pick up unencrypted text; use your PC as a spammer; and the list goes on. These things could be on your PC right now.

So relax, the virus on your PC is not your fault. Do what you can do to protect your PC, but tell IT you know that all viruses aren't your fault.

Dino Londis is a BYTE technologist specializing in the consumerization of IT. He's also an IT pro working at a Manhattan law firm. Email him with ideas (but not legal questions) at [email protected].