It can scan files on your hard drive, snoop on other applications
(such as chat programs or word processors), install further download anti spyware
free programs, and read cookies, relaying the information it
gathers back to its author. It's really quite difficult to tell if your PC is infected
with malware or if the symptoms are caused by other legitimate
reasons such as software or hardware incompatibilities or system instability.
A computer virus is a self-replicating program which installs
itself on your computer without your consent.