HEAD OF STATE (PG-13, 95 minutes)

Comic Chris Rock directed and co-wrote this illogical, haphazard but awfully funny sendup of American politics in which he plays a city alderman who runs for president. Aside from Rock's fans, high schoolers fascinated by elections and modern American history will love all the pointed barbs in this knowing farce, with its urban edge and rap star cameos.

PG-13 is apt for the occasional profanity and sexual innuendo -- crude but not graphic. Rock's usually R-rated stand-up patter is held in check, but he doesn't seem stifled. The movie makes assassination jokes, though, which could unsettle younger teens not yet into irony.

Rock plays Mays Gilliam, an activist from Washington, D.C., with diamond ear studs and attitude. Power brokers from the Democratic party see him on the news and cynically tap him to replace their recently deceased presidential candidate. Why? Because they want him to lose. Gilliam's opponent is a vice president whose slogan is "God Bless America -- and no place else!" His handlers (Lynn Whitfield, Dylan Baker) try to script him, but his brother (a hilarious Bernie Mac), a flashy-dressing bail bondsman, tells him to speak his mind. The polls soon change.

THE CORE (PG-13, 135 minutes)

An exciting sci-fi flick despite underwhelming special effects, "The Core" has vivid characters, great dialogue and smart direction by Jon Amiel. Teen fans of science and science fiction should enjoy the ride because the fantasy comes alive and the stakes seem monumental. The premise is that the Earth's core stops rotating, causing the planet's electromagnetic field to go haywire, threatening total destruction in less than a year. The PG-13 reflects non-graphic scenes of violent death -- heart pacemakers stop, birds swarm, cars crash, microwave rays melt bridges. A spectacularly authentic-looking crash-landing (non-fatal) of the space shuttle could upset some. Rare profanity and smoking also earn the rating.

Aaron Eckhart plays a brilliant professor who first recognizes the problem. He's brought in by the government to head a secret emergency mission to save the world. He teams with a shuttle pilot (Hilary Swank), a weapons specialist (Tcheky Karyo), a vain scientist (Stanley Tucci) and a genius inventor (Delroy Lindo) whose Tootsie Roll-shaped ship will careen the "terranauts" toward the Earth's chewy center. There they attempt to jump-start the core with nukes. The computer-generated images of what they're supposed to see down there look more like human innards than geological ones, but no matter. "The Core" is a total trip.

BASIC (R, 95 minutes)

John Travolta's terrific performance as a roguish DEA agent investigating a military base murder carries this little mystery over the foggier stretches of its deliberately opaque plot. And the ending gives the dangling threads a neat surprise yank.

Whodunnit-loving high schoolers may like the way this mildish R keeps re-creating the murder from various points of view. The violence, often understated and stylized by director John McTiernan with antsy camera moves, does include a gross poisoning death, shootings and fights. The script contains profanity and some sexual innuendo.

Travolta plays Tom Hardy, a former Army Ranger turned jolly DEA agent, currently under a cloud for suspected bribe-taking. He's called to a Ranger training base in Panama to help a grudging, less-experienced investigator (Connie Nielsen) find out why a hated drill sergeant (Samuel L. Jackson) has turned up dead following a jungle exercise. It's fun watching his cagey Hardy zero in on the truth.