A decade after they reinvented hip-hop, Public Enemy no longer bring the media noise the way they once did. But after a falling-out with their longtime label, Def Jam, P.E. are now once again wearing redwood-size chips on their shoulders. There’s a Poison Goin On. . . . initially came out as an Internet-only release and rails against the usual cast of hapless subjects: the record industry, Uncle Sam, black radio stations, hip-hop itself. “I’m the reverse of jiggy/All that prettiness,” human howitzer Chuck D spits on “Here I Go,” while Flavor Flav, still the freshest second banana in hip-hop, ducks in and out like rope-a-dope Ali. Actually, there is some jigginess on this record: Chuck’s sometimes self-righteous bitterness is tempered by R&B melodiousness on “World Tour Sessions.” But the emphasis is on sparser, more spacious mixes — less claustrophobic and dizzying than Bomb Squad-era P.E., but still gripping. The stoner metal of “Do You Wanna Go Our Way???,” the Last Poets-like agit-rap of “Crayola” and the cold-sweat horn bleats of “First the Sheep Next the Shepherd?” suggest that a little midlife crisis is just what P.E. needed.