This morning, my PC hits several Microsoft deadly "blue screen". After reboot it into safe mode and scanned with latest Microsoft Malware Scanner, discovered some trojan in my PC. I think this is the root caused the PC to be halt in dedly states.
A computer virus is a
computer program that can copy itself and infect a computer without permission
or knowledge of the user. The original may modify the copies or the copies may
modify themselves, as occurs in a metamorphic virus.
A virus can only spread from
one computer to another when its host is taken to the uninfected computer, for
instance by a user sending it over a network or carrying it on a removable
medium such as a floppy disk, CD, USB drive or by the Internet. Additionally,
viruses can spread to other computers by infecting files on a network file
system or a file system that is accessed by another computer. Viruses are
sometimes confused with computer worms and Trojan horses. A worm, however, can
spread itself to other computers without needing to be transferred as part of a
A Trojan horse is a file that appears harmless until executed. In
contrast to viruses, Trojan horses do not insert their code into other computer
files. Many personal computers are now connected to the Internet and to
local-area networks, facilitating their spread. Today's viruses may also take
advantage of network services such as the World Wide Web, e-mail, and file
sharing systems to spread, blurring the line between viruses and worms.
Furthermore, some sources use an alternative terminology in which a virus is any
form of self-replicating malware.
The term comes from the term virus in
biology. A computer virus reproduces by making (possibly modified) copies of
itself in the computer's memory, storage, or over a network. This is similar to
the way a biological virus works.
Some viruses are programmed to damage
the computer by damaging programs, deleting files, or reformatting the hard
disk. Others are not designed to do any damage, but simply replicate themselves
and perhaps make their presence known by presenting text, video, or audio
messages. Even these benign viruses can create problems for the computer user.
They typically take up computer memory used by legitimate programs. As a result,
they often cause erratic behavior and can result in system crashes. In addition,
many viruses are bug-ridden, and these bugs may lead to system crashes and data
There are many viruses operating in the general Internet today, and
new ones are created and discovered every day.