Looking at Common Virus Symptoms

Stalking the wild computer virus starts with observation: There are a lot of ways that a computer can begin to act strangely for no apparent reason. These changes in behavior may be the result of a virus, but there are other possible explanations as well.

This article describes some typical virus-induced symptoms, as well as some ways to determine whether a virus is responsible for your computer’s symptoms.

Computer too slow

The first thing to check when your computer is slow is to make sure that your computer isn’t in a school zone. Seriously, a slowing in your computer can be the result of a number of circumstances — and a virus is definitely among them. The following list provides some considerations for making an educated guess as to why your computer is slowing down:

 Have you made any changes to your computer lately?
For instance, have you upgraded to Windows 2000 or Windows XP? These newer operating systems require a lot more memory than their predecessors.
Have you upgraded a program? Like Windows 2000 and Windows XP, newer versions of many other programs like Microsoft Office and Microsoft Works require a lot more memory than earlier versions.
Have you or a loved one downloaded a lot of “nature” pictures or other information? Pictures and music take up space. If your hard drive is almost full, your computer will definitely run slower.

If you’re sure you haven’t made any changes, then you may have a virus. You’ll have to check your computer’s behavior and run a number of simple tests before you can be sure.

Unexplained activity

Does your hard-drive or network-activity light flicker for no apparent reason? While there may be a legitimate reason for it, this could also be a sign that a virus or a hacker’s back-door program (a devious little program that allows secret access without your permission) is running on your computer. You might be donating some of your computer resources to a hacker and be largely unaware of it. Here are some examples of what could be going on if a hacker has gotten control of your computer:

  •  The hacker could be using your computer to send thousands, even millions, of those annoying spam messages to people all over the Internet.
  • The hacker could be using your computer to launch attacks on corporate computing networks. In a DDoS (distributed denial of service) attack, for example, a hacker instructs thousands of “zombie” computers (like yours, perhaps) to send lots of messages to a particular corporate Web site, glutting its communications and knocking it off the Internet.
  • The hacker could be using your computer to scan other networks, hunting for vulnerable ports (communication channels for particular computer processes) that can mean more potential-victim computers.
  •  The hacker may have installed spyware that reports back to the bad guys without the victim’s (your) knowledge. One example is a key logger — a small program that records every key press and mouse movement in an attempt to learn your bank-account numbers, credit-card numbers, and other sensitive information that you proba- bly don’t want strangers to know about.

Crashes or hangs

Does your computer crash often? Does it just stop responding? Do you often get the Blue Screen of DeathTM? Again, there are many possible explanations. No cop-out, just reality. (Hey, if I had a crystal ball, I’d quit writing, buy office space on Bourbon Street in New Orleans, and make my fortune, right?) Crashing, hanging, and blue screens may be virus-induced, but they’re probably not. These maladies are more likely the result of new software, new drivers, or even a hardware component that’s beginning to fail. Check out those possibilities first.

Will not boot

Boot used to be a noun — the leather thing you put on your foot to protect it from rough terrain. These days boot is a verb just as often; it’s the process that your computer performs to start itself when you turn it on or press Ctrl+Alt+Del (the “three-finger salute”).

You guessed it — just because your computer won’t boot, it doesn’t necessarily mean that your computer has a virus. Maybe yes, maybe no. There are several other likely explanations — for example, a corrupted master boot record (the part of the hard drive that your computer uses to start up), or damage to an important file that your computer uses to start up.

If either of these was the case, you’d probably have to rebuild your computer’s operating system and file system from scratch — not fun, even for the experts — and recovering any lost data could get dicey in a hurry. But you know, if you’re running Windows and have to reinstall your computer’s operating system, here are a couple of basic improvements to consider:

  • What better time to upgrade to Windows 2000 or Windows XP (unless you’re already running one of those)?
  •  What better excuse to curl up with a good book — say, whichever Windows For Dummies book covers your newly installed version? This could be the perfect opportunity to read up on Windows while you’re waiting for the install to finish.

Strange computer behavior

Okay, computers sometimes behave inscrutably, but their behavior should be predictable. Same deal for viruses — which means they can’t completely conceal their activities.

You can look for the devil in the details. Perhaps the signs are obvious (the colors go all weird, the computer puts words on-screen by itself, or it makes strange noises) or relatively subtle (your screen borders pinch inward for an instant just before you send e-mail). Time to observe closely and take notes. For openers, consider some “obvious” symptoms: 

  • Files are not where you left them, and can’t be found on your computer. If your computer has become a Bermuda Triangle that is eating your files, even some of your software, you might have a virus.
  • You can find the file, but its size or date stamp is suspiciously different. Viruses that infect program files may make the files bigger or smaller than they should be, or change their date stamps. Date stamps don’t ordinarily change on program files — ever — unless an official software patch changes them. Uh-oh.
  • On-screen text starts to change by itself. In the old days of the DOS command prompt, one virus made the letters in on-screen text seem to move around “by themselves.” Sometimes they changed colors, or started consuming each other like Pac-Man. Bad sign. But you knew that.
  • An out-of-context message appears on-screen. Some viruses announce their presence by taunting the user. If you are greeted with a message such as Your computer is now Stoned! , you probably have a virus. Consider whether the message is out of context — for example, does it look like someone’s trying to cap a practical joke with a punch line? Not funny at all.

Too many pop-up windows

While I can’t prove it, I’d suspect that in some cases, Web sites that flood you with pop-up windows could also be attempting to download some malicious program(s) into your computer. Web sites that pump pop-ups into people’s computers are notorious for attempting to change the configuration of your Web browser and other parts of your computer — by remote control, without your knowledge or permission.