Q. I bought an anti-virus program and it found a virus on my machine and eliminated it. Now my computer is as slow as the social life of a computer geek.

A. There are two issues to worry about here: residual files and programs that run in "real time."

Some viruses, even after you've killed them off, can leave behind extraneous files. Many are identified on your hard drive with the extension ".tmp," which stands for temporary files. Lots of Internet files that got there legitimately (most of them help create graphics on your screen) have that extension, too.

Having a boatload of these temp files can slow things down and they must be removed periodically for optimum performance. You can do that manually by telling Windows Explorer to search your hard drive for "*.tmp" files. Most current anti-virus programs will do a pretty good job of removing any residual files left by a virus, but you may have to inspect to get them all.

Anti-virus programs run in the background while your important programs are in use. This is frequently referred to as operating in "real time." If you take a normal machine and install a program that scans for viruses, it may slow the performance of the computer.

Chances are, however, that the anti-virus program is only a minor load on system performance. What's happening is that the slowness is pointing out areas of your computer that need to be improved: by adding memory, upgrading or cleaning out your hard drive, or--worst-case scenario here--dumping your Jar Jar Binks screen saver.

Hey, Computer Guy--you were wrong about that Netscape answer last week.

Last week, a reader wanted to know how three people could use one machine's Netscape e-mail and retain private access to the mail. My answer was that there was no "easy" way. However, I will reluctantly admit that there are some twisted, roundabout, Rube Goldberg methods that might, possibly, offer some kind of security.

Here's one way:

Buy a 100-megabyte Zip drive and connect it to your machine.

A normal installation of Netscape assumes that all the files are stored on the hard drive. But you could buy a Zip drive and put a copy of Netscape on a Zip disk instead. This way, when you want to use Netscape e-mail, you can pop in your Zip disk and run the program from it. Your messages are stored on the disk, which you can take with you when you're done.

Other readers have said that programs like Magic Folders (pc-magic.com/dl.htm) or Postman Office 1.1 (www.netsoftdesigns.com) can help you set up private folders for messages. But I am very wary of them because they really aren't mainstream yet.

I will stick to my guns: There is no "easy" way.

I use America Online and just got the message "Cyber Patrol Code 0.8" on the screen. What's that?

It means someone has installed a "filtering" program called Cyber Patrol on your machine and you have tried to connect to a prohibited site.

The Internet has an incredible variety of Web sites, many of which, needless to say, you'd rather your kids didn't visit. As a result, many parents invest in Web filtering software that blocks access to certain sites.

Cyber Patrol 4.0 from the Learning Company (www.learning co.com) is a highly rated program. You buy it for $39.95 and it prevents your children from surfing to sites that contain nudity, profanity, drugs, intolerance, violence and gambling. You can also create user profiles so that different kids have access to different types of sites. You get free weekly updates for a year (the company has a staff classifying sites as they come and go). After that, an annual subscription is $29.95.

Cyber Patrol does a good job, but it's not unbeatable. What happens if Johnny goes next door to surf on a non-filtered machine? I think parents should unplug the computer and plug themselves into the lives of their kids.

John Gilroy of Item Inc. is heard on WAMU-FM radio's "The Computer Guys" at 1 p.m. on the first Tuesday of the month. Send your questions to him in care of The Washington Post, 1150 15th St. NW, Washington, D.C. 20071-5302 or via e-mail at jgilroy@iteminc.com.