White guys with backward baseball caps and lousy attitudes aren't the only ones who shouldn't jump genres. It goes both ways. On his long-delayed "rock album" Rebirth, rapper Lil Wayne replaces hard hip-hop beats with soggy guitar riffs and primeval drum thumps straight outta 1999. "American Star" even launches the album with a semi-scorching fret workout that could have been hiding in Eddie Van Halen's closet all these years. But Rebirth quickly falls into a hard-rock trap. Either Weezy has lousy taste in rock or he actually believes this is what it sounds like. His sole contribution to the genre? Auto-Tune. Only "Drop the World" (as in "I'm gonna pick the world up and drop it on your fuckin' head") manages to pack some weight. Just as Fred Durst and dozens of other rap-rock clowns could never quite grasp the fundamentals of either music, Lil Wayne temporarily abandons his rap throne for a record that mistakes volume for power.