Answer Line: How Can I Tell If My PC Has Caught a Virus?

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My sister tells me that I'm sending her virus-laden e-mail. What's more, something is slowing down my computer. Do I have a virus?

Name withheld by request

Neither of the symptoms you describe is conclusive proof that your system has a virus, although the slow PC could indicate the presence of one or more malicious programs.

Don't worry about your sister's complaints. Viruses seldom reveal whose computer is actually sending them. They commonly fake the 'From' address of the e-mail, often using an address found on the infected PC's hard drive. The virus probably came from an infected machine belonging to someone who knows both of you; it sent itself to every address on the hard drive, randomly picking yours as the "sender."

On the other hand, be very suspicious if your PC uploads files over the Internet without your approval. Much malware today sends info from your PC, either to spy on you or to use your PC to send spam or a virus. Make sure your firewall is set to stop and report on all outgoing activity you haven't explicitly approved. Windows XP's firewall doesn't provide this functionality, so if you don't already own a security suite or stand-alone firewall that can handle the job, I recommend that you get Zone Labs' ZoneAlarm or Sygate Personal Firewall, either of which is free for personal use.

You might discover hints of an infection in the System Configuration Utility, also known as Msconfig. To open it, click Start, Run, type msconfig, and then press <Enter>. Click the Startup tab. In the list of programs that load automatically when Windows starts, look for one whose name resembles an eye chart; many malicious programs rename their files with random character strings. Others, though, mimic the names of real system components.

If programs like Msconfig, the Windows Registry Editor, and your antivirus program don't load, your PC is almost certainly infected (although these programs sometimes act up for reasons other than a viral infection). For details, see my August 2005 column, "Prevent Viruses From Disabling Your Protection."

Free online virus scanners can help you find the culprit if your regular antivirus program is compromised. I recommend (see Figure 1

Figure 1: Check your system for viruses online in case your PC's own antivirus program has been compromised.
), Kaspersky Lab, and Trend Micro.

USB Cable Myths Busted

How do I tell whether a USB cable is the old version 1.1 or the newer, faster 2.0 version?

John Hisato, Vallejo, California

If a cable has a "USB 2.0" label, it's obviously a USB 2.0 cable. The label tells you that the cable has been tested to meet all of the appropriate specifications. Without the label, it's hard to know. (There was never a "USB 1.1" label.)

Most USB cables, even those that predate 2.0, support 2.0 performance--but not all do. Well-made cables, especially those longer than 2 feet, are usually thicker and stiffer than substandard cables. A thin and flexible 2-foot cable will probably handle anything you transmit, but a similar 15-footer may slow you down.

Using a cable that isn't up to the job won't hurt anything except performance. If a file transfer is taking hours instead of minutes, you should switch to a better cable. Otherwise, don't worry.

Boot Without Windows

Can I boot from a CD, surf the Web with Mozilla Firefox, and read e-mail using Mozilla Thunderbird, all in a virus-free environment?

Name withheld by request

Yes, but not with Windows. Various versions of Linux, referred to as "Linux Live," can boot from a CD or flash drive. I recommend Puppy Linux. It's free (not unusual for Linux), small, and very easy to set up on a CD. Putting it onto a flash drive isn't hard, either.

You can download Puppy Linux. A number of versions are available; I recommend puppy-2.00-seamonkey.iso. Double-click the file name to launch your CD authoring program and burn the bootable disc.

To install Puppy Linux to a flash drive, boot from the CD, click the desktop, select Setup, Install Puppy USB drive, and follow the directions.

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