ANSWER LINE: How could my protected PC have gotten infected with Trojan horses?

摘要

[...] do you really have the best security software? Be suspicious, Don't click links in a dubious e-mail message, If a program you didn't install and launch tells you your PC is infected, assume it's about to infect your PC, Download software only from reputable sites. [...] every week or so, scan your hard drive with an alternative antimalware program to get a second opinion. Show less