As a computer consultant, I get to see common problems that your average user faces when using their computers.  One that I hear frequently is;  "I was browsing the net last night and now I keep getting all sorts of popups and spyware warnings.  I don't know what I did.  How can I fix this?" 

First, you probably didn't do anything to cause this problem!  And, if you did, the software should have informed you prior to allowing the nasty issue to occur.  One of my pet peeves is that some of the computer industry has people blaming themselves for buggy or insecure software!  Don't fix it, blame the user! I digress.  Back to the question.