Often .EXE files my friends send me look quite scary to me. I notice how many people they are sending them to. If one of these computers has a virus and the person owning it saves the program and sends it to others, they will very likely all get infected copies. The virus may be one that does nothing for a long time, so it may get sent to many others before anybody suffers any damage. In fact, if a program is traded widely enough it can pick up several viruses as it passes through infected machines. All this occurs, usually, without any of the participants being aware of it, not only as they pass the files on to their friends, but even later if they find they have viruses. There will probably be no clue to tell them where the virus came from or that they sent it to others.

I have to assume that these files were sent through many computers before my friend got them and that they may already be infected. The fact that all those people have seen no sign of infection means very little. Most viruses remain quiet for some time or until some date.

Many virus checkers can detect many viruses, but most cannot detect new viruses until they become known to the checker, and no virus checker can detect what I'm going to tell you about now. Computer viruses do not simply happen opportunistically as organic viruses do. People write (devise and construct) computer viruses in order to harm others. Having produced a virus, its creator looks for a way to distribute it anonymously to many people. One of the best ways to do this is to hide it in a fun program that people will want to share with others, and then get this program sent to as many people as possible. Note that this program is not an infected program. No virus checker will be able to find the virus in this program. The program does not have the virus (is not itself infected). It is, instead, a program that produces the virus. It may not produce the virus until a certain date long after many people have been enjoying it. Then, one day, perhaps the 100th time you run it, it generates the virus, and from that time on, any program you send to anybody is infected.

Also, keep this in mind whenever you receive an e-mail with an attachment you do not expect. Recently, one was sent out with a fake senders address of somebody at Microsoft. The letter claimed to have an important file from Microsoft but actually contained an e-mail worm.

I could simply ignore attachments I'm unsure of but somehow that seems dishonest. It seems to me that the way to be a better friend is to tell people what I know. I don't want to be one who spreads panic or mistrust or steals the fun from cyber-socializing. For a while I thought it was kinder to say nothing. One person that I told all this, would call me every time somebody sent her a .EXE file and would have me talk her through deleting it. I wondered if I had caused her worry for no reason. Then, one day she received HAPPY99.EXE, a known virus, and I knew I had saved her more trouble than I caused. Another person I sent this to assured me that, having been a programmer many years, he knew how to protect his computers. A while later I couldn't reach him and, when I finally did, he told me he had been out of touch a couple months and lost his address book because of a virus - and he didn't know how he got it.