Inside the starship shaped like Eddie Murphy, the Captain (also played by Murphy) barks orders in a set that superficially resembles the bridge of Star Trek: The Next Generation. It soon transpires that the ship has been critically damaged in the crash and has less than two days of power remaining to find the device that will doom our world and save theirs. It also turns out that the longer the ship walks among among humanity, the more our human emotions infect its crew, and the more their previously robotic personalities evolve into human analogues that include internet nerds, drunken partiers, bootylicious ladies and flamboyant but supportive gay best friends.

In the great tradition of plotting by insanely ridiculous coincidence, the Starship attempts to cross an intersection against the light and is run down by, out of all Manhattan’s millions, Gina Morrison (Banks), a pretty single mom whose young son treasures the precious McGuffin as a personal good luck charm. I mean, seriously, what are the odds? Literally, millions to one. And again, what the odds that the walking starship will pause for a maintenance check, in the alley right outside the bedroom window of that widow’s young son? Millions piled on millions.

And finally, what are the odds that Gina will not find this stranger’s behavior odd, and that she will invite him up to her apartment and further offer him some breakfast?

It’s impossible to stress that last point any more clearly. It’s a well-worn and by now long-accepted tradition that the beautiful female lead of over-the-top Hollywood comedies will write off any amount of bizarre or stupid or demented behavior on the part of the male lead, and will probably fall in love with him to boot, whether the explanation for his behavior in any particular movie is that he’s an alien or a robot or just (as is most often the case), just an inept slob who’s lucky he learned how to tie his shoes.

As audience members, we have to accept this, even if, in real life, most women who look as good as Gina are forced to develop radar that warns them away from the most obvious percentage of creeps and predators. It’s not always good radar, but it’s usually, you know, rudimentary. So it’s highly doubtful, to say the least, that an intelligent young mom would be quite so pleased to come home from shopping and find the strange guy she spoke to for five minutes earlier that morning, now on her couch playing video games with her young son. This is especially true of Dave, who drinks ketchup from the bottle, kicks her cat, clears her table by sweeping the dishes off with his arms, speaks in strange non sequiturs, and has bizarre mannerisms that would lead any woman not the female lead of a silly summer comedy to judge him as peculiar or demented or a victim of severe neurological impairment. And yet, it’s not long before she regards him as a prime-choice romantic prospect. Go figure.

A New Kind of Eddie Murphy Vehicle

Remember when the name Eddie Murphy above the title was not a warning label? This reviewer does. And for an exceedingly brief time, Meet Dave almost looks like Murphy’s about to deliver a comedy worthy of the efforts that cemented his stardom, in the lamented days before Daddy Day Care and Norbit and Pluto Nash. The starship’s early, clumsy attempts at walking among humanity and its bizarre, off-kilter attempts to mimic human behavior as it interacts with the various denizens of planet Earth are often forced but sometimes genuinely funny. For the first half hour or so, this is enough to deliver amused chuckles at the rate of one every minute or two. Unwary audiences might find themselves hoping that the rest of the movie can maintain the pace.

Then the plot starts to kick in, and you start to notice that nobody in the film, including Murphy himself in captain guise, delivers a performance anywhere near as effective as Murphy playing the spastic starship. And the thing is, they all should. Ed Helms proved on The Daily Show and continues to prove every week on The Office that he’s one of the comedy elite; here, he’s a mugging nonentity who fails to elicit a single laugh. Elizabeth Banks is appealing as a warm-hearted, sexy widow, (and, says the pig of a reviewer, fine eye candy), but the performance is all surface, with not a single cell of meat to it. And all the other supporting performances are similarly off. After a while it becomes clear that the players have little to work with. The laugh moments grow fewer and farther between. And hence we come to the rule oft-noted but worth repeated: special effects comedies cease being good at the moment when the special effects, and not the performances, are asked to carry the weight of the comedy.

There are a couple of effective set pieces, best among them a brief interval where The Captain and his cultural officer and shipboard romantic interest Number Three (Union) have to survive at street level while fighting to get back to the ship, but for the most part the laughs grow fewer and farther between, to the point where the final half hour provokes frenzied watch-checking.

Worst of all: when the dialogue turns to such skiffy tropes as the special creature that is humanity, and the life-affirming emotions that represent our greatest and most enduring gift to alien civilizations that never learned how to feel -- trust me when I say that no Spielberg film or incarnation of Star Trek, no matter how gamey, ever plucked the strings of that particular theme with as much determined syrup as Dave does here. It’s enough to give Diabetes to two civilizations.