When searching, you may have been surprised by pop-ups appearing on some sites, informing you that your PC may be infected with a virus and needs scanning. In many (perhaps most) cases, this is part of a scam.  The scammers create sites that will appear high in rankings for many types of search. What might happen if one clicks on a link within the pop-up is alarming: the web browser links to a web site that is controlled by the scammers. The site then loads a fake Windows security alert which pops up suggesting that your PC contains virus infections and an invitation to “prevent attack” by clicking on another link. This leads to an offer to sell you clean-up and protection software — which is bogus, will cost you money and, even worse, may install “key logging” software that can intercept passwords and other confidential information, sending this to the scammers.  If you encounter such a pop-up, do not click on anything – not even the “Cancel” button. Even this, apparently innocuous, action may be enough to install the scamming software imperceptibly in the background. Instead, force your browser to quit: press “ctrl-alt-delete” to navigate to the Task Manager, then locate the application running the fake alert and force-quit it by clicking “end task.”