Where: Theaters everywhere.

When: Opens today.

Rating: PG-13 for sexual content, partial nudity and language.

Running time: 97 minutes.

Bottom line: A romantic comedy whose supporting players have more spark than the leads.

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As a product of Hollywood's romantic-comedy assembly line, "Failure to Launch" is notable because it's loaded with accessories but doesn't have an engine.

Matthew McConaughey, he of the ripped abs and three-day-stubble, plays Tripp Winslow, a 35-year-old single guy in a state of arrested adolescence. He still plays the field romantically, always ending relationships the same way - by bringing the woman to his place, which happens to be his parents' house.

Yep, Tripp still lives with Mom (Kathy Bates) and Dad (former NFL star Terry Bradshaw), and why shouldn't he? Mom cleans his room, does his laundry and cooks pancakes for breakfast. But Mom and Dad aim to nudge Tripp out of the nest, so they hire an "intervention specialist," Paula (Sarah Jessica Parker), who has a foolproof program for dating guys to build their self-esteem to the point where they'll move out of the basement.

Paula's irresistible force has yet to reckon with Tripp's very immovable object. But as he's starting to fall for her, she does the unprofessional thing and falls for him.

Why do Tripp and Paula fall in love? Nothing in the script by sitcom scribes Tom J. Astle and Matt Ember suggests these two would actually hook up under normal circumstances. There also are zero sparks between the laid-back McConaughey and the uptight Parker. It seems the only reason these two are together is because they're both on the movie poster.

But while the central couple is a bust and director Tom Dey's slapstick and offputting humor (like showing Terry Bradshaw's buttocks) are rather forced, "Failure to Launch" has some great stuff on the edges. You could build a whole different movie, and a much better one, around Paula's snarky roommate Kit (Zooey Deschanel) and Tripp's computer-geek pal Ace (Justin Bartha). Their story is funnier, more original and more endearingly romantic than anything McConaughey and Parker do together. Alas, the Hollywood assembly line can't handle a romantic pairing that unusual.

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