Memo to Beyoncé Knowles: You were so good as Etta James in Cadillac Records, so why’d you go spoil everything with a rank cheeseball thriller that buries you in clichés and won’t even help you dig yourself out? I’d call this stenchcloud “Fatal Attraction meets The Temp,” but that would insult those movies. Movie? Obsessed doesn’t move at all. It lays there like undigested latkes. Beyoncé Knowles (she uses two names for movies) plays Sharon. She’s happily married to asset manager Derek (Idris Elba), once on fire with The Wire and now reduced to a situation dire. OK, I’ll stop. But the movie doesn’t. Everything you need to know is in the trailer. Derek gets hit on by Lisa (Ali Larter), a temp from central slut casting. He resists her jiggly butt and pert breasts. This is the kind of no-balls movie where the guy is a saint, even before the temp turns psycho stalker. So where’s the conflict? Nowhere. Screenwriter David Loughery and director Steve Shill, a TV hack (who’d have guessed?) have built something silly and shockingly unsexy (a wimpy PG-13 rating for this kind of trash — whaat?) all in the name of big, climactic catfight that should been camp fun but is no fun at all. Beyoncé does go medieval on what she calls Larter’s “skinny white ass.” She also calls her “crazy ass bitch.” Obsessed is crazy-ass also. Crazy-ass awful.