At about 11:20 eastern time, a Cessna 172R lost power while landing at Greenwood Lake Airport and crashed -mile from the runway. The CFI and commercial pilot sustained minor injuries. The flight had originated at White Plains, N.Y., and had entered the traffic pattern for landing at Greenwood Lake. While on the base leg at 800 to 900 feet agl and with power set at 1,900 rpm, the pilot tried to apply power but the engine did not respond. No pre-impact anomalies were found and the engine was successfully run after the accident. Service Difficulty Reports for the Cessna 172R revealed 58 submissions regarding momentary engine roughness or intermittent loss of engine power, which have occurred both in-flight and during taxi, since June 1998.