How can I tell if my computer has a virus? If you can answer
"yes" to any of the following questions, your computer might
have a virus. Is your computer running very slowly? A common
symptom of a virus is much slower than normal computer
performance. However, there can be other reasons for slow
performance, including a hard disk that needs defragmenting, a
computer that needs more memory (RAM), or the existence of
spyware or adware. For more information about spyware, see How
to tell if your computer is infected with spyware. Are you
getting unexpected messages, or are programs starting
automatically? Some viruses can cause damage to Windows or some
of your programs. The results of this damage might include
messages appearing unexpectedly, programs starting or closing
automatically, or Windows shutting down suddenly. Is your modem
or hard disk working overtime? An e‑mail virus works by sending
many copies of itself by e‑mail. One indicator of this is that
the activity light on your broadband or external modem