Normally the night watchman is the one you expect to see dozing on the job. In Night at the Museum it's the talent behind the camera and consequently members of the audience who grab forty winks and don't awake from their slumber until the final reel, when the comedy livens up considerably.

The guard in question is Larry Daley -- a thin disguise for the hapless fellow Ben Stiller routinely plays. If not for decent special effects, a smattering of gags and one-liners, and a geriatric twist, what could have been a delightful romp based on Milan Trenc's childrens' storybook would be a totally botched opportunity. The idea of exhibits at New York's Museum of Natural History coming to life every night offers fodder for raucous and even informative screen humor. This haphazard effort is guided by a docent with problems focusing. A better battle plan might have papered over its illogical aspects or at least topped it up with more fun.

Perhaps screenwriters Robert Ben Garant and Thomas Lennon tried to follow the Writers' Guild audiotape tour of how such a film should go down. Or maybe their scheme was shredded in the editing room. Either way, precious time is wasted establishing a character we already are familiar with in order to set up a trite progression by which a father proves himself to his son and the world at large. By ditching the early scenes, three nights in the cultural establishment could have been stretched to a couple of weeks, thereby letting the idea breath and spreading out the good bits more evenly. 

By now virtually every moviegoer targeted by this comedy knows Ben Stiller always plays a loser. Even the diminutive Mickey Rooney gets to use him as punching bag here. Larry is an under-achieving dreamer and amateur inventor whose ex-wife is engaged to a rich techno-dork (Paul Rudd) and who's an embarrassment to his son. The sequences defining his sad sack personality wouldn't be expendable if they were funnier and if Stiller didn't look so bored on discovering Larry's car has been booted, taking a hockey puck to the head at his son's practice, or visiting the unemployment office to scrounge for a job -- any job -- so that junior isn't further disappointed. 

The clerk, played by Stiller's real-life mother Anne Meara (looking more sleepy than exasperated) sends him to the museum for a job interview with Dick Van Dyke's amiable head watchman, who's about to retire along with two equally long-in-the-tooth colleagues played by Rooney and Bill Cobbs. On his first night, Larry discovers that all the exhibits spring to life when the sun goes down, courtesy of an Egyptian tablet. He's besieged by a T-Rex that wants to play fetch, Mayans with poison darts, Attila the Hun, Roman Legions led by Octavius (Steve Coogan), and prospectors from the American West whose ringleader is played by an un-credited Owen Wilson.

Robin Williams is all bully as Teddy Roosevelt, who clues Larry in and keeps his spirits up. Larry's objective is to rein in the chaos and stay in tact until the sun comes up. All's well if the exhibits stay within the museum walls. Carla Gugino plays a docent writing her doctoral dissertation on the Indian guide who helped Lewis and Clark. Not even her obvious crush on Sacajawea can stop the obligatory romantic connection with Larry.

Not until three-quarters of the way through when a moderately surprising development forces Larry to prove his mettle is the energy sustained. The puzzle is why we have to wait so long enduring boilerplate scenes and lulls before he's put into this position. Ricky Gervais (of the original, British The Office) has some amusingly off-the-wall shtick as the officious museum director, a font of non-sequiturs forever losing his train of thought. Perhaps he was the guy asleep at the controls. 

(Released by 20th Century Fox and rated "PG" for mild action, language and brief rude humor.)