Kelly McGillis, beguiling new girl in town, steals whatever excuse for a show there is to steal tonight in "Private Sessions," a mournfully simplistic two-hour NBC movie (at 9 on Channel 4) that also serves as the pilot for a potential series starring Mike Farrell, one of the least interesting actors of our time but also, he is always reminding us, one of the most "concerned." With a capital "con."

As Dr. Joe Braden, a Manhattan therapist, Farrell is the consummate Muppie -- Middle-aged Urban Professional. He jogs, he works out on Nautilus machines, he plays the clarinet for relaxation, he eats falafel at lunch, he's trying to maintain a friendly relationship with his ex-wife, and his adorable daughter has presented him with a basset hound he mock-grudgingly adopts.

Let's face it: Joe's the kind of guy who could bore you to death during a two-minute elevator ride.

But into his office tonight comes McGillis as patient Jennifer Coles, suffering from a bad but dramatically exploitable case of chronic nymphomania. She even seduces a guest at her father's birthday party! Later it evolves that the father (Robert Vaughn, still snarling after all these years) is to blame; when Jennifer was 9, she was molested by one of Daddy's clients, and his refusal to believe her, and his insistence on ignoring the incident, caused her slavery to sexual impulses.

It's a textbook case, one that would scarcely be a challenge for The Playboy Advisor, but McGillis, who made a very noticeable movie debut in "Reuben, Reuben" and is a current sensation in "Witness," gives Jennifer an affecting sense of harried desperation. She certainly does know how to use accusing eyes. However, if Jennifer were a real person, she would have walked out of the doctor's office just minutes into her first visit, when this ridiculous exchange occurs:

Jennifer (shaking nervously): "Is it all right that I smoke?" Dr. Joe: "No." Jennifer: "Why not?" Dr. Joe: "Those are my rules." You don't have to be a suspicious sort to perceive from such twaddle that Mr. Missionary Mike Farrell had some sort of input into the script by Thom Thomas; thus does the character, who is supposed to appeal to us as a common-sense regular (Dr.) Joe, come off as a sanctimonious priss.

As a series, "Private Sessions" would apparently be a landlocked "Love Boat," with guest neurotics spilling their guts and getting tidy prescriptions for happiness, even though the pilot feigns indignation at mass-marketed shrink-think. Tonight's other walking problem is Tom Bosley as a cab driver suffering headaches and hallucinating "voices." But Dr. Joe is on the case! The guilty party turns out to be the cab company, which has installed in its cabs new carpeting treated with a toxic chemical that induced the symptoms.

Among the cutesy details supplied for the series are Maureen Stapleton as a kind of Mother Freud, the psychiatrist who shares offices with the hapless therapist, and even such contrived foils as a funny ethnic doorman with whom the good doc exchanges limp quips. It's all about as appealing and genuine as the acidic grin Farrell tries to pass off as a smile. Essentially he's playing the same angel-sent-to-earth that Michael Landon plays on "Highway to Heaven," but Landon is a pillar of believability by comparison.