It used to be said of the Phoenix Theater in London that it hadn't had a hit since the Blitz. Jennifer Aniston's career is starting to feel the same. Billed as "America's sweetheart" for this generation (as well as playing a latter-day Debbie Reynolds for the gossip rags, as she bravely watched a bigger star steal her man), the ex-Friends star has made one decent film, The Good Girl, and a string of duds thereafter. For being one of the highest-paid performers in Hollywood, you wonder why she isn't a tad more careful about projects.

If Aniston were on a personal quest for the bottom, one would have thought that she couldn't get any lower than last year's Rumor Has It, a patently unfunny comedy co-starring Kevin Costner and the earthly remains of Shirley MacLaine. But here is The Break-Up to prove that it is possible to reach a point below "beneath contempt."

As humorless as Rumor, The Break-Up also manages to be unbelievably retrograde. It is the type of sex comedy that needs a strong screwball sensibility that hasn't been much apparent in films since Carole Lombard's plane went down. But in the genre's classic age of the 1930s and '40s, the partners were at least witty and attractive. Here we have a young woman, Brooke (Aniston), who has hitched herself to a schlub named Gary (Vince Vaughn), and who is starting to feel strangely slighted by him. She cooks, cleans and mothers him continuously, and all she gets in return is heartache and rejection. What's a girl to do?

Brooke decides to leave Gary (as much as she can in a shared condo), but only to teach him a valuable lesson in sharing and caring. Really, she wants him back ever so much, and will consent to any girlish subterfuge toward this end. She will date other men in an attempt to inspire him with jealousy; she will even submit her mons veneris for depiliation (in a procedure dubbed the "Telly Savalas") as a means to draw the male gaze away from its Schlitz, Doritos and Gameboy.

It's difficult to feel sympathy for Brooke's plight, as anyone with functioning self-respect would have ejected this slob from the couch ages ago. But, it's love, you see, and they have put up with so much from each other already. Gary hails from a close-knit Polish-American family, all of whom seem to have based their diets around kielbasa. Brooke is from a fey, arty family — indeed, her brother Richard, who leads an all-male a cappella choir, may actually be gay (this truly is the level of humor on offer here).

Aniston invests Brooke with her own collegiate common sense and practiced opened-mouth astonishment at the real world. Vaughn has more regard for his character than most will, and strives to find a sensitive heart beating under all that bear meat. Ann-Margret makes a cameo appearance as Brooke's mother, and the excellent Judy Davis provides whatever comedy exists in this flick as Brooke's brittle boss, Marilyn Dean.

The Break-Up, however, is an old-hat "couple's comedy," even though it tacks a bittersweet ending onto the affair. It may be caddish to say, but if Aniston wants to make sex comedies, she'll need to seek out innovations to the genre — as her cruel ex and that other woman managed to do with last year's Mr. and Mrs. Smith (whose title paid homage to Alfred Hitchcock's great '40s screwball film of the same name with Lombard and Robert Montgomery).