Q. You always write that a virus check should be done "from a floppy." How do I do that?

A. First, let's ask, why should I do that?

When you flip on your computer and drum your fingers waiting for something useful to appear on the screen, many activities are taking place behind the scenes. One is that your computer is looking at the A: drive (the floppy drive) to see if there's a disk with special data that it requires to "boot," or get running. If there's no disk there, it goes to the C: drive (the hard drive) to find the boot information.

"Boot sector" viruses like to take up residence in these key areas. They are so clever that they can mask themselves from anti-virus programs that are stored on the C: drive--think of them as similar to Klingon cloaking devices. Booting from the A: drive helps to unmask these digital demons.

So, to boot from a floppy, go to a machine that you are sure is virus-free. Make a "boot disk" from this machine. There are various ways to do this, depending on what operating system you're using. Check the manual.

Then obtain a current version of an anti-virus program. Inside the box you'll find a floppy--variously going by the name "magic bullet," "emergency disk," "utility" or "SOS."

Now put the boot disk you made into the drive and turn on your computer. When the machine gets up and running, pop the disk out and put in the disk from your anti-virus program. There is normally an ".exe" file on this disk that you run to begin the search for viruses.

By the way, this is a Federation-approved method to defeat any Klingon cloaking device.

I've got an older Pentium with Windows 95. Can I get USB capability without buying a new PC with Windows 98?

Yes, but you may need a crowbar and a few magic incantations.

Many readers are interested in USB, or universal serial bus, a fast new way to get data in and out of a personal computer. If you've got a new machine, you can see the USB ports--two small rectangular connections on the back.

Some older Pentium machines don't have these ports. But you can overcome that hurdle by going on the Web to www.belkin.com and ordering a PCI/USB adapter, for $40 to $50.

Windows 95 was released in three iterations, what we common folk call A, B and C. Each version added capabilities; both the B and C versions can handle USB. If you've got them, you can use USB.

Although everything I have written so far is technically correct, you may still run into a lot of headaches. In the world of high technology, using USB under Windows 95 is referred to as "flaky." Your USB device may not have the stability it will have under Windows 98.

I and several other people at my office use the same computer for Netscape mail. Is there any way to password-protect our individual mail accounts so that anyone who boots up can't read my mail?

No simple way I can think of.

Eons ago, computers were expensive and it was common for several people in an office to use one machine. Given how little you have to spend on a computer these days, I was kind of surprised to get this question.

What this person is doing is opening Netscape on the machine, connecting to a server and downloading e-mail from it after entering a password. The mail is stored on the machine's hard drive. Several other people do the same. They may all think that their mail is protected by the password they entered, but once it reaches the hard drive, it isn't.

With many e-mail programs, security is based on access to a machine. A password can be put in a machine's BIOS chip so that you have to know the password to use the machine. But once you're using the machine, you can read all the e-mail on it.

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.