Few things in life are as humiliating as starting to tell a joke and then forgetting the punchline.

But that's what seems to happen to "Analyze This," a gangster-in-therapy comedy that starts out funny but quickly loses its way. And worse, the film changes its focus from an interesting character to a less-than-interesting one about midway through.

Also, be warned that it's all very R-rated, with a near-constant flow of profanities coming from the mouth of Robert De Niro and a surprising amount a violence, as well as some other humor that is in questionable taste.

In fact, given the content and how extreme some of the situations get, it's hard to believe "Analyze This" came from Harold Ramis and not Quentin Tarantino.

That said, it is an interesting premise, and the pairing of stars is nearly as interesting. (The movie teams De Niro with Billy Crystal, another actor whose career has been on the slide in the past few years).

De Niro plays Paul Vitti, a powerful New York gangster who is next in line to become the leader of his crime "family." And while he's thrilled to be taking the place of his late mentor, Vitti suddenly starts having paralyzing panic attacks.

Enter Ben Sobol (Crystal), a New York psychiatrist who lives in the shadow of his much-more-famous father (Bill Macy), also a psychiatrist. That changes in a hurry when Ben is involved in a fender bender with Vitti's right-hand man, Jelly (Joe Viterelli).

To Ben's surprise, the big thug doesn't fly off the handle. Instead, Jelly recruits Ben to treat his trou- bled boss. The trick is, Vitti doesn't want to reveal too much of himself — and he's under the impression that Ben should be on call 24 hours a day.

As mentioned, it's a nice setup, but the story wanders all over the place and introduces far too many characters and situations — none of them tied up satisfactorily in the end.

On the performance side, De Niro's mood swings are very funny and it's nice to see him parodying some of his earlier work. But there's just not enough to the character. And Crystal's standard shtick gets tiresome in a hurry.

The supporting cast is a similarly mixed bag. Viterelli is fine as the lug with a heart of gold, but Lisa Kudrow is one-note.

"Analyze This" is rated R for considerable profanity, violent gunplay and some fistfighting, use of vulgar slang terms and some sexually based gags and jokes, simulated sex, partial female nudity and ethnic slurs.