The other day I heard a friend complain that he spent nearly 4 hours to argue with Norton support people for he couldn't understand why he should paid extra 160 dollars to fix Norton's mistake. It happened when my friend clicked on a game site called "Play Sushi.com" and then he tried to get the website off but he failed. He immediately ran a full system scan with Norton but the anti-virus found nothing.
From then on, his computer was getting slower and slower and had pop-ups. When he explained his issues with Sushi, the guy immediately said it was a virus and my friend should pay $160 for a tech guy to look into it, for Sushi had not any responsibility to fix the virus problem for my poor friend. Well, if it was a virus, why Norton anti-virus which my friend had paid (not expired) found nothing while the computer did meet problem? Norton didn't play its role as an anti-virus obviously here.
The above story could have been a lot worse. I also knew a friend whose Mcafee was disabled by a kind of virus and his computer was fully controlled by the blackguard virus.