How on earth did my PC at home got infected by a Backdoor Virus in the presence of an updated anti-virus software and a personal firewall? This is the second time that my PC got infected by the Trojan backdoor virus, which causes my PC to automatically shutdown by itself. The last time my PC had the virus, it left me with no choice but to re-format the system. I don't want to go through the hassles of re-formatting and installing programs again. And so, I am searching a much reliable anti-virus that can quarantine and delete the entire virus from the system. As far as what my present anti-virus program does, was just to "heal" the infected file. I dunno what exactly heal means, and i presume that will already stop my PC from shutting down by itself for the meantime.