It seems like Eddie Murphy wants to live in a world of his own. Increasingly, in movies like the execrable Norbit, he plays multiple parts and does his best to make sure that any parts played by other actors are bland and forgettable. He plays only two parts in his latest film, “Meet Dave,” but he has found a way to live in a world of his own — literally. He plays the captain of an alien spaceship that plans to steal all of Earth’s oceans. And he plays the spaceship itself, a white-suited humanoid structure designed to move about New York to find their missing ocean-sucking orb.

The aliens are tiny by Earth standards and it takes dozens of them to operate a human-sized spaceship. The cultural officer (Gabrielle Union, warm and elegantly beautiful as always) uses Google to explain what is going on and provide the captain with answers to questions he is asked. When he is asked for his name, she does a search of Earth’s most common names and he answers “Ming Cheng.”

The person asking his name is Gina (Elizabeth Banks), who accidentally hit the spaceship with her car and is trying to make sure what she thinks is a person is all right. When she says he looks more like a Dave, he tells her that his name is Dave Ming Cheng and he begins to befriend Gina and her 5th grader son Josh (Austin Lind Myers), and discover that the Earth inhabitants are not the useless barbarians he expected.

As “Dave” and, through him, his crew begin to interact with the earthlings they experience food, shopping, mochitos, salsa dancing, 5th grade bullies, and “A Chorus Line” (a couple of bars is enough to bring out the inner effeminate homosexual in a formerly macho weapons expert). They get a little drunk and they start to feel emotional.

The kids in the audience enjoyed the silly stuff, as when “Dave” ducks into an Old Navy changing room to manufacture American money out of his boxers. But director Brian Robbins (Norbit, Ready to Rumble) allows the film to sag between its weak and too-infrequent punchlines and has no idea of how to work with talented performers like Banks, who has not much to do other than a nervous laugh, and Union, limited to longing or impatient glances. Murphy seems angry and impatient with the material and the other performers. As horrible as Norbit is, at least it tried to build on the bitterness and insularity Murphy increasingly projects. Murphy manages a good silly walk but his best moments here only remind us of his better films, especially “Coming to America,” another fish-out-of-water story set in New York. These days, Murphy seems like a fish out of water as an actor on screen.