"I went on this great site last night... and now I've got a virus/trojan!"

It's late at night. Creeping downstairs (so as not to disturb the wife), you slink into the living room, intent solely on your goal - a bit of late night surfing. Time to go on those sites that you know you shouldn't - like that one that Dave in Accounts sent you the link for. Surreptitiously, you enter in the website address, and click the enter key...

... Only to find that your computer has now spawned more windows than Everest, and is intent on letting the whole world know that you went on sheepsh*ggers.com - oh, and is that the sound of your beloved's sweet footfall on the stairs on her way to investigate what the scream of "NOOOOOOH!" was all about...

OK - for our third (and final) part of this article, were going to look at what to do if you suspect you have a virus or Trojan. The first question I'm often asked is "what's the difference?". Well, a virus is a program that is intent on replicating itself to other computers without the user's knowledge, in a similar way that a real virus infects your body, and passes itself on to the next person (like the flu). A Trojan (named after the famous wooden horse of Troy) is a virus that wants to do more than just replicate - it wants control of your computer for it's author's use, and by it's definition, a Trojan is more serious.

The first thing to do is to ascertain if your computer is infected. The best way to do this is also the best way to fix it, and by that, I mean "scan your computer for viruses". If you haven't already done so, install a anti-virus solution like AVG, and run a full scan for viruses. Once the scan has finished, you'll have the option of either quarantining the viruses found, or removing them from your computer - either is an acceptable solution.

Now that you've installed / run your anti-virus solution, make sure you keep it up to date by downloading the latest virus signatures - if you don't do this on a regular basis, all the hard work you just did will be undone very quickly, so check your anti-virus's documentation on how to keep up to date.

The next thing is to search your computer for Adware - these are programs that are not technically Trojans, but are the next best things - programs that want you to buy a product, by hijacking your PC and pointing you to the authors website. Because Adware is specialized, you'll need a specialized tool to deal with it - my favourite is SpyBot S&D, because it's thorough, and it works. Install it, update it, and run a full scan, then fix any errors it finds.

9 times out of 10 the above methods should sort you out. If they don't try looking at www.pchell.com - here you'll find lot's of useful information on viruses, Trojans, and other annoying PC specific problems that may be affecting you.

Right, I'm now off to disinfect my computer - with a blow-torch. You can't be too careful you know...