Inside very well lighted gym, other photos taken but when shooting a small group in same location the shutter locked up. ISO/ASA 200, f6, auto focus, flash off as with other photos taken and the shutter locked up. Had the same problem when shooting a flower outside on sunny day: ISO 200, f3.5 to throw background out of focus, set on auto focus. Shutter locked up. battery was charged, lens on correctly.
См. статью: What might cause shutter lock up on Nikon D90 after taking others with no problems?