Infectious Grooves, Sunday, September 3, at Fiddler's Green, headlines Gra-fx, one of the last shed-sized alterna-festivals of the season (also on the bill are Voodoo Glowskulls, Stanford Prison Experiment, Sincola, Sinister Dane, Lord of Word & the Disciples of Bass, Sick, El Dopa, the Reejers, Da Bush Babies and Love Lies). But while the event seems on paper to be another faux Lollapalooza in extreme-sports clothing, the Grooves are the real thing. Led by Mike Muir and Robert Trujillo (both members of Suicidal Tendencies), the band is at its best on its latest disc, Groove Family Cyco. The material on the album is deafening, danceable and powerful enough to shred all those other pretenders to the Red Hot Chili Peppers' punk-funk throne. This is one infection we hope is never cured.