You see a pop-up message on your computer that tells you your computer has a virus. The message may look similar to legitimate anti-virus software messages. In some case, the fraudster is trying to sell you bogus security software that does little or nothing. In other cases, this fraud may involve illegitimately capturing credit card information, or installing malicious software such as a keystroke logging program. If you click to accept a download, you have likely allowed the installation of malicious software and given control of your computer to the fraudster.