Katherine Heigl has dropped out of contract talks with bosses of hit medical drama GREY'S ANATOMY over a salary dispute. The star plays DR ISOBEL 'IZZIE' STEVENS on the show and is reportedly upset she is receiving less money than her co-stars. A source tells American publication People, "Katie is disappointed and hurt that (the show's producer) Touchstone doesn't value her as much as her other co-stars, especially Sandra Oh and Isaiah Washington. Sources on the set also say tension has emerged after a spin-off series was announced featuring Kate Walsh's character, DR ADDISON MONTGOMERY. A source tells American publication Star, "The rest of the cast seemed instantly resentful of (Walsh). "They each thought they'd be the one chosen to get their own show, and now they're giving Kate the cold shoulder."