At 0950 Pacific time, a Lancair LC42-550FG operated by Lancair as a business flight, veered off the runway during the landing roll at Roberts Field and collided with a taxi sign. The pilot, flight instructor and two passengers were not injured. The flight departed from Bend, Oregon, about 10 minutes prior to the accident. The pilot said he flared about four feet above the runway and the stall warning horn sounded. He chopped the power and the aircraft rapidly descended to the runway. The pilot then applied full power and the aircraft veered to the left. The flight instructor got on the controls in an attempt to regain runway heading. The flight instructor called for the pilot to reduce power but the aircraft exited the runway and the right wing collided with a taxi sign.