Hats, high altitude, and freezing cold weather do not a good hair day make. And those are the exact conditions stars are facing at the 2010 Sundance Film Festival. Luckily, celebrity stylist Patrick Melville is set-up at the Aveeno Style + Shine pop-up salon for impromptu touch-ups—and Kristen Stewart, Malin Ackerman (left), Renee Zellweger and America Ferrera have been taking advantage. What look did Melville give rocker-chic Stewart? "It's a simple blow dry with a little pomade and spray," he said. As for Ackerman, she just came in for a freshen-up. "I flipped her head over, put in some Aveeno Volumizer hit it with a blowdryer and finished with shine spray for instant gloss and volume."