Back in ancient times I designed memory systems to be resistant to bit flipping involving cosmic rays. It was in conjunction with a computer that used a 286 processor, the same one in use in the suspect flight systems. Our solution was to use error detecting and correcting memory. This architecture used extra memory bits that would allow any single bit error in a memory word to be corrected on the fly. The technology was mature at the time the flight control computers were developed. Does anyone know if memory correction technology was used on the Boeing flight control computers? If so it would rule out random bit flips as an error condition.