Yet another 23-minute TV sitcom stretched out to feature length for the big screen, "Problem Child" is a problem movie. There are amusing moments here and there and John Ritter offers an ingratiating performance, but that's about it.

This film is essentially a very broad, cartoony parody of "The Bad Seed," despite its dark basis. Yet it never really takes off in a "Naked Gun" or "Spaceballs" direction, settling instead for the gentle but not very funny familiarity of a sunny TV style, which seems like an odd choice given the subject.

For the audience it is necessary right off to put aside any realistic feelings about abandoned children, serial killers and adoption. If making fun of such things offends you, go in some other direction.

Ironically, the abandonment of the title character under the opening credits is one of the film's more amusing moments, a series of scenes with "Junior," as he's called, being left as an infant in a basket on a wealthy doorstep, and then with each offense he commits being taken to another doorstep that is a little lower in social status — as he rapidly outgrows the basket.

This is a very smart way to begin a movie like this because it tells the audience immediately that a few sacred cows are going to be punctured. But first-time screenwriters Scott Alexander & Larry Karaszewski and first-time director Dennis Dugan settle from that point on for jokes that range from merely silly to insipid, with a few cheap vulgarities thrown in.

When Junior reaches 7, he is played by young Michael Oliver, a boy so precocious that he deliberately wreaks havoc everywhere he goes. He is in a Catholic orphanage at this point, terrorizing the nuns. He also writes letters to his pen pal, a jailed murderer known as the "Bow-Tie Killer" (Michael Richards), whom he emulates by wearing a bow tie.

Meanwhile, across town a married couple — John Ritter and Amy Yasbeck — have been trying unsuccessfully to have a child. Eventually they decide to adopt — Ritter because he wants a son to love and Yasbeck because she feels she is a social outcast as the only childless resident in the neighborhood.

Of course, they will adopt Junior and Junior will set out to destroy their world.

Most of "Problem Child" is pretty flat. John Ritter is the only cast member who creates a character with any weight, playing a "nice guy" — so naturally everyone around him considers him a dweeb. But even he occasionally succumbs to the histrionics employed by the other cast members — especially Yasbeck, who is constantly over the top.

As the only female character of substance in the film, Yasbeck plays an extremely negative stereotype — the shrill, social-climbing wife who eventually has an affair and in the end runs away with the serial killer.

As Junior, young Oliver seems a bit stiff at first, but he did grow on me as the film progressed. (He may remind you a bit of Ronny Howard as Opie on the old "Andy Griffith Show.") Michael Richards also gets a few chuckles as the manic murderer.

Director Dugan, a former actor who has a bit in this film, along with his screenwriters, for some reason felt the need to include a number of tasteless gags, including an adult mooning a TV camera, two jokes each about urinating and flatulence, etc.

The children in the audience laughed in several places, enjoying the slightly raunchy parts more than most of the older moviegoers. But are jokes like these really appropriate for kids?

One wonders what someone like Mel Brooks could have done with a premise like this. There still would have been vulgarity, but there would likely have also been a number of inspired hysterical moments.

As it is, "Problem Child" never comes close .

It is rated PG for gunplay and vulgarity.