MAKE A BACKUP BEFORE DOING ANY MAINTENANCE. Actually you should do a backup regularly anyway.








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Computer Virus Information
Revised 7-6-16

Wondering about computer virus? What, Where, Why, How, Who? All will be answered in layman's terms.

Understanding what a virus is

First a simple definition. A computer virus is to a computer as a human virus is to a person. It makes you sick in varying degrees depending on the strength of the virus and your ability to withstand it.

A computer virus is a program written by a programmer just like the programs you use regularly. They infect your computer in a variety of ways depending on how the program is written. Programs are stored in a computer file. You should educate yourself about the naming of computer files if you are not currently so. There are many good books that describe this process.
Also be sure to check my page on Computer File Extensions for some pertinent information.

See my new discussion about spyware for more ways a virus can harm you.

Just as a human can be inoculated against a virus, so too, the computer can be inoculated.

Also as with humans, avoiding a virus is possible. With humans, we stay away from people places that may transmit a virus. With the computer, we can avoid contact with a virus with a few simple precautions.

Another analogy between human and computer virus' is that the inoculation can make you sick. Many avoid taking a flu shot for fear of getting the flu. Experts agree that it is not possible, but many disagree. In the case of a computer inoculator (referred to as an Anti-Virus program), It is my personal opinion that the inoculator does cause more damage than the virus it is intended to defend against.

One great difference between these two is that human virus' are not created on purpose. All computer virus' are created on purpose with malcontent in mind.

One question I get asked frequently is WHY? Well can you tell me why punks spray graffiti on other peoples property? The mentality is similar. It is also a competition thing among their peers to see who can inflict the most damage. Ever watch kids compete in a video game room? That spirit of competition extends with a rare few into the world of creating havoc.

Every technician in the world will tell you to install and run an anti-virus program, so I used to be a loner in saying not to. Note: I changed my mind on this. Check this link to see why.

Whether you run an antivirus program or not, you should RIGIDLY follow the rest of my advice to avoid a virus in the first place. Especially the one at the bottom regarding Go Back. This does not mean you should not have an anti-virus program, just don't let it run automatically all the time. I'll discuss how to look for a virus later.



The advice in this page is meant for home users primarily. Business users have only limited control over the office computer and cannot implement many of my suggestions.

I offer this advice as what I believe has worked well for me over the years for my own computers and those of my students and clients. I assume no responsibility for any damage caused from following the recommendations herein.

How does a computer get a virus?

Remember a virus is a program (or a little piece of one) so therefore it is carried just like any other program or piece of computer information as a file. We store files on disks (floppy, hard, CD, DVD, Zip and others) and then transfer them to another computer. We attach files to e-mail. We transfer files in numerous other ways from one computer to another. A virus can be transferred from one computer to another the same way. After all, they are just computer files.

Therefore, A virus can be transmitted from one computer to another via a disk, an attachment to e-mail, through a network and somehow activating the virus. If you are careful about the files you take into your computer, you reduce or eliminate the chance of getting a virus.

Preventing a virus

Let's take the various ways a virus can get into your computer one at a time starting with the least common.

1. On a disk. Any disk can carry a virus. If you copy files onto a floppy, Zip, CD, Etc. on one computer and then use the floppy in another computer, you could transmit the virus. The only way to avoid this is to check any disk with an anti-virus program. Be sure to see my cautions later about using an up-to-date checker.

Remember that any purchased program can carry a virus as well, so to be sure, check any disk before using it. I do not follow my own advice here because in 20 years of home computing, I only saw it happen once and on a Microsoft release at that. The odds of it happening are very low as long as you buy from reputable companies.

2. Through a network. This did not present a problem for the home user until recently with the explosion of broadband Internet services. If you are using DSL or Cable modem, you are exposed to a network continuously. Actually anyone one the Internet is exposed, but the danger from regular modem is much less.

A virus can be avoided in this method by running a firewall program. You can get one free at If you need help learning how to download and install programs from the Internet, click here. And yes, you can get a virus from a downloaded program too, but it rarely happens because any reputable site would lose a lot of business if they let it happen, so a lot of precautions are in effect at the download sites.

There are other precautions to take when you are on wideband connection to the web. Your hard drives should be passworded to prevent access by unwanted parties. I haven't created instructions on how to do this yet. If you need to know how, send me an EMAIL. Use the link at the bottom of the page.

3. The most common way a virus is transmitted is via an attachment to an e-mail. This is a complex subject, so sit back and take notes.

My first rule is DON'T OPEN ANY ATTACHMENT. If you follow this advice, you will probably never see a virus. Obviously this is not completely practical, so I will add some recommendations later.

We used to say that you could not get a virus from opening and reading e-mail. It is still true with an exception. Using Microsoft Outlook or Outlook Express can allow a virus to infect your computer without even opening your mail. Microsoft has tried to close the gaps that allow this and offered suggestions on configuring the program to reduce the possibility. One thing that has to be done is to download a new update to the program frequently. Big headache, but if you are stuck with the program as in an office situation, you have no choice.

I think a much easier answer is DON'T USE OUTLOOK. If you need an e-mail program on you local computer, consider using Netscape or Eudora, both free programs. Eudora does have paid versions for serious users, but for normal home use the free version is plenty powerful.

The best answer is to use an online e-mail program like Yahoo, Hotmail, Gmail or many others offered free. My preference is Yahoo since they make checking an attachment for a virus very easy (I have avoided a number of them lately thanks to Yahoo) and they don't have a limit on the amount of storage. Gmail is also quite popular. Gmail does have a limit but most folks never reach it. Gmail does allow one feature that Yahoo does not. Putting a picture in an email is easy with Gmail. Yahoo does not allow it. You can attach it but not imbed it. Lastly Gamail will not allow anyone to send you an email with an EXE attachment. Yahoo does. Yahoo just scans the file for a virus.

For additional information on e-mail, click here.

Opening attachments

Never opening any attachment is the safest way to avoid a virus. Attachments are never safe, even from people you know, unless you know what to look for.

First a file attachment is identified by a file name and extension. If you know the person sending the file and the file appears to be a picture, is it safe to open?

NO!!! ......IT IS NOT!!!!!

First of all, many well meaning friends have passed on a virus thinking it was a cute little program. A classic example was the Navidad virus passed around at holiday time. It displayed a cute video on your screen. The damage was being done behind the scenes. The file was being sent to everyone in your address book. Then when you try to restart the computer, it was dead, preventing you from warning everyone you just sent it to.

A more recent example was a virus that takes all your documents in the My Documents folder and sends copies to everyone in your address book. Boy did that cause some problems. Think about it.

Preventing Problems

A number of things must be done to avoid getting a virus.

1. If you have an anti-virus program and want to use it, you must download and install the latest virus definition files from the web. We used to say monthly was sufficient, but now weekly is barely enough.

If you do this, check any suspect file before opening it.

2. If you use Yahoo e-mail, scan any attachment before opening it.

3. Most importantly, set your Windows preferences to show file extensions. The latest trick of the virus scum is to hide a virus behind an apparently harmless file. Let me explain. In the past, we said that a picture file cannot carry a virus. This is still true, but you must be sure the file is really a picture. Here is an example:

Would you say that "myphoto.jpg" is a picture? It would appear so, but as a famous movie once said, "It ain't necessarily so". Suppose the file name was really "myphoto.jpg.vbs"? Now what would you say? The problem with file names is that by default, Microsoft wisely hides file extensions from view. This was done as a protective feature for the inexperienced user to prevent changing files and making them unusable. Now the virus programmers are using that against us, so we need to change that option. It is easy to do. Just follow these instructions:

The process varies slightly depending on what version of Windows you use. Open My Computer. Look through the menus for "Folder Options". It may be under View or Tools. In the Folder Options dialog box, click the "View" tab and look for the box that says "Hide File Extensions" and uncheck the box. Then the complete file names will be displayed so you won't be fooled by a double extension.

4. I like to use an online virus checker anytime I need to scan something. This is especially effective for those of us on a broadband connection. (Scanning attachments in Yahoo e-mail is using an on-line virus check.) The advantage of using an on-line check is that you are using the absolutely latest data file to recognize the latest virus.

Many virus software suppliers provide varying degrees of on-line checkers. Look at Norton (Symantec) and McAfee. Check my websites list for addresses. My favorite is the free checker by TrendMicro at Setting it up the first time takes a few steps, but is worth it. I have found virus' on clients computers that were passed up by the other programs. Their main page at has a lot of good info on virus problems with definitions and problems.

To get a free anti-virus program, Click Here for AVG by Grisoft or Here for Avira and Here for Avast

Clicking on takes you to Trend Micro. They sell a program called PC-cillin aimed primarily at business. They provide a free on-line scanner called HouseCall. Look for the menu item "Free Tools". Follow the screens and look for House Call for PC's. At the next screen, you can choose to scan without registering or register if you want information on real virus, instead of the hoax e-mail you get from your well meaning friends.

The next screen shows all the drives on your computer and begins downloading the latest definition files. You may get a screen asking to allow them to install an add on file. Click Yes. When the download is done, check the box by your hard drive or check the floppy, CD or Zip to scan any drive. Be sure the disk is in place. Also check the "Auto Clean" box. Then click scan and sit back and watch.

If you have a cleanable virus, it will tell you. If you have a non-cleanable virus, it will be listed. If you have any of these, highlight them and click delete after the scanning is done.

On rare occasion, a virus file may not be deleteable. This requires some extra effort. Be sure to write down all the information. If you are comfortable with Cut and Paste, place a copy in your wordprocessor and print it.

Then close all programs, using CTRL-ALT-DEL. Look for the file using Find (or Search in Windows Me) and try to delete it. If it still won't delete, you may have to restart in Safe Mode, find the file and delete it. If this does not work, you will need some instruction in starting the computer in "Command Prompt Only" mode and use old antiquated DOS commands to find and delete it .

And Finally, NOT ALL VIRUS' ARE REAL. MOST ARE A HOAX. See my page on hoaxes and check it out before warning anyone about a potential virus.

What to do if you get a virus

This really depends on which virus you get and how much damage it has done. The first thing I do is scan for the virus files with the on-line scanner provided you can still get on line. If this finds the virus, you should be able to delete it as described above. You can also get info from any of the sites about the virus including how to clean your computer.

In the event you can't even start the computer or get on line, it is best to take it to a professional. One alternative you can try is to download a Boot disk on a working computer. All of the major antivirus companies have them. Some work better that others. Do a Google search for antivirus boot disk for the latest info.

One drastic step that may need to be taken is to reformat the hard drive and reload all programs. If this happens, you better hope you have backed up all your data in advance.

Any of these solutions can be time consuming, frustrating and maybe expensive. There are other ways to make sure you have ability to reverse a problem. You could keep a regular image of the last working version of your system using programs like Akronis. Always keep backups of your data & photos because you may get a virus that crashes you so bad you have to reload Windows from scratch.

One final discussion:

I have always repeated the comment from experts that "You can't get a virus from a true JPG". That is no longer true. There is a virus called Perrun that can infect computers through JPG files, so even pictures are not safe anymore. Check out these links: and for more info.

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