COMMITMENTS : Cybervillains Beware--Someone’s Watching You : Computers: Private investigator Lynn Zwicke has signed on to protect the gullible and unsuspecting. The mother of six also tells parents what their kids are doing on-line.

Prodigy, whether it likes it or not, has its own private eye.

Lynn Zwicke, a 44-year-old widow with six children, is a licensed private investigator in Milwaukee who prowls the Prodigy bulletin boards to warn the gullible and unsuspecting, and to bust those who would prey on them.

She never intended this to be her major avocation. She signed on to Prodigy for fun and relaxation from a patently stressful occupation.

But she quickly noted the sometimes frantic postings from parents whose teen-agers had been recipients of unsolicited pornography, and from women who unwisely gave their home addresses to a friendly Pnut (as Prodigy aficionados call themselves) and ended up unwilling victims of a putative stalker.

With cooperation from the agency that employs her (and trained her), Zwicke turned her investigative talents to the on-line service. She has found, confronted and reported to Prodigy officials shadowy figures who sign on to different boards (“Teens” or “Lifestyles,” for example) with various names, genders and self-descriptions. She can’t remember the last time she read a book, she says with a sigh.

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Prodigy officials know Zwicke is there and permit her pro bono activities even though they believe the problem is smaller than has been portrayed. They encourage parents to adopt the policy of “turn them in and turn them off”--that is, alert Prodigy officials to the posting and turn off the computer--when they come across suggestive or offensive postings or E-mail.

On-line services have been likened to big cities with good neighborhoods and bad neighborhoods, but, says Prodigy spokeswoman Debra Borchert, “It’s a lot easier to escape on a computer than it is in a public place.”

Zwicke identifies herself on-line as a PI, but when she has a suspect in her sights, she may sign on as one of her children or someone in search of on-line companionship.

She also posts warning notes urging parents to find out what their kids are doing on-line, warning people never to give out personal information--especially addresses, passwords and credit card numbers. Now she is trying to organize parents and schools off-line to alert teen-agers to on-line perils.