Are you scared of your own shadow when it comes to computer threats?

Do you protect your systems against viruses, spyware, cookies, Trojans, worms, hijackings and other nondescript threats to your privacy and personal well-being? I hope you do.

Yet with each new protective software product we place on our systems, we slow them down -- sometimes just a hair, other times by large amounts -- as they monitor the data coming in and flowing through our Internet connections.

Is it necessary? Yes. It would be truly inappropriate to take your virus scanner off your system if it is connected to the Net, or even if you just exchange diskettes or CDs. Viruses can come from anywhere, even from people you know and trust, and they can have devastating effects on your system and personal time.

But not all the threats are as bad as they seem.

One of the most maligned computer concepts is the cookie. Cookies were conceived in the early days of Netscape, the first universally popular Web-browsing software. An astute programmer realized that the World Wide Web has a remembering problem.

The Web is a connect-and-disconnect type of system. Every time you want a Web page, you call it up with your browser, either by typing in the name of the page or clicking on a link. Then, as soon as the browser sucks the page into your system, it disconnects from the computer that originally held the page.

This frees up the Internet for lots of connections. But it makes your connection to the Internet a bit dumber. Because you use separate connections with each Web page, the people on the other end can't really tell that you are the same person viewing the next page as viewed the first page. That makes it more difficult to serve you proper information and to remember what you just did. It's even tougher if you close and reopen your browser.

Cookies are one way to solve that dilemma. Web operators often place them on your system every time you read a page. When you request the next page by clicking on a link, the Web site can read the cookie, determine that you are the same person who read the first page, and deliver the proper content based on the information in the cookie. It's like leaving a trail of cookie crumbs as you traverse the Web.

Many companies that operate password-protected Web sites use cookies to remember your user name and password from session to session. If you wipe out your cookie, the Web site will ask you for your user name and password the next time you log in -- even if you asked it to remember you.

Microsoft's online help uses cookies to remember your recent help requests and related information, making follow-on questions and subsequent help requests faster and relating them better to your specific needs.

Other companies and individuals use cookies in more obnoxious ways. Various advertising networks use them to track you from Web site to Web site, subsequently building a profile of you and your habits.

This rubs people the wrong way, so they remove the cookies en masse using antispyware programs. Each time you run your antispyware program using default options, you are removing the good cookies along with the bad. That's why your favorite Web site doesn't always recognize you.

Keep using your antivirus and antispyware software. But learn how to read the results of your antispyware software so you recognize its mistakes and adjust accordingly, saving the good cookies as you eliminate the bad. You will find the time well spent.