If you use the internet (and if you're reading this then it's pretty safe to assume you do) then you run the risk of your machine getting infected with malware. Infection vectors are wide and varied, and even a website that you've visted 1000 times before and you thought was safe could be loaded with malware the next time you click. There are some great documents and discussions on this site on how to stay protected, but even with the best defence mechanisms there is still unfortunately a chance that something nasty will slip through the net.
Most malware these days, somewhere down the line, is money-driven - be it from attempting to swindle you into buying fake anti-virus "software" or paying ransom money to have your files decrypted (and then selling on your credit card details too), or by stealing your online banking password or intercepting transactions in the browser. And where there's an illicit opportunity to make money, there will generally be people willing to take that opportunity - so the new malware just keeps on coming.
Some infections are easy to spot - if you have Fake-AV or Ransomware then you'll know about it . Others are stealthier and lurk inthe background doing their best to go un-noticed, and it's only when you check your bank balance that you see something untoward has occurred.
There is help at hand though, it's totally free and it's available for you to use if you think you've got an infection on your pc:
Stinger is McAfee Labs' free standalone removal tool - it is released on a daily basis and at the time of typing this it covers nearly 6000 malware familes, including Vundo, Autorun.worm, Xpaj, ZeroAccess, Blacole, Zeus and a whole host of FakeAlerts, Backdoors, downloaders, password stealers and banking trojans.
It might just be the droid you were looking for....