MERIDEN, CT–All her life, Janet Hartley has suffered from a host of ill-defined viruses and inexplicable aches and pains, diagnosing herself with everything from diabetes to cancer. But ever since discovering such online medical resources as WebMD, drkoop.com, and Yahoo! Health, the 41-year-old hypochondriac has had a whole new world of imaginary illnesses opened up to her.

Janet Hartley learns more about her suspected case of arteriovascular malformation on Yahoo! Health.

"The Internet has really revolutionized my ability to keep on top of my medical problems," said Hartley, speaking from her bed. "For instance, I used to think my headaches were just really bad migraines. But then last week, while searching Mt. Sinai Hospital's online medical database, I learned about something much more serious called cranial AVM, or arteriovascular malformation, which, along with headache pain, may also result in dizziness, loss of concentration, and impaired vision. I immediately thought to myself, 'Hey, that's exactly what happens to me.'"

In addition to regularly surfing various general medical-reference sites, Hartley makes frequent use of medical-school research sites, drug-company FAQs, and bulletin-board services for terminally ill patients in her ongoing quest to self-diagnose her hypothetical maladies.

"No more thumbing through the two-volume Physician's Desk Reference, a repetitive motion which led to my carpal tunnel syndrome," said Hartley, her wrists wrapped in ointment-soaked Ace bandages. "It felt great when I could finally throw that old thing out. Except I think I slipped a disc in my back tossing it in the trash can."

Every day, provided she feels up to it, Hartley logs onto the Internet from her home. She also frequently logs on from work.

"Something in my office just isn't right," Hartley said. "I always feel fatigued there, and for a long time, I suspected that the fluorescent lights were leaching the vitamins from my system. But according to a bunch of web sites I checked, that's unlikely. Then I thought maybe it was asbestos in the walls, but supposedly, there isn't any. So I spend some time on the Internet every day trying to figure out what exactly it might be."

A web page Hartley visited to learn more about the symptoms of Parkinson's Disease.

With a vast array of medical resources available to her at the click of a mouse, Hartley has been able to investigate workplace maladies ranging from office-chair-induced lumbar-vertebrae displacement to the carcinogenic properties of coffeepot residue to the possibility of spinal-fluid poisoning resulting from carpet-fabric outgassing. But perhaps Hartley's favorite thing about the Internet is its ability to connect her with other hypochondriacs.

"Just the other day, I was at the chronic-fatigue-syndrome message board, talking to other sufferers like myself," said Hartley between coughing fits. "I can't tell you how reassuring it was to be in the company of people who are not only going through the same things I am, but who know I'm not just making this stuff up."

Despite her enthusiasm, Hartley cautioned that Web-based medical diagnosis remains an inexact science.

"It's still far too common for a person who knows she's sick to enter her symptoms and get a response back from the web site that says nothing's wrong," Hartley said. "If that happens, you should get a second opinion from a different site. Or maybe take stock of your physical state again. You may have missed something that would alter your diagnosis. Or, if a web site is asking you 'yes or no' questions about the symptoms you're experiencing, just say yes to all of them. That way, you'll get a wider list of diseases, conditions, or syndromes you might have."

Hartley offered one final caution. "Computers are great, but if you spend too much time in front of them, you run the risk of developing chronic ocular strain," she said. "Not to mention the threat posed by monitor radiation, which I suspect played a part in my recent brain-cancer scare. Fortunately, though, if a computer makes you sick, you can then use it to help you get better."