We have a 25 question quiz comprising multi-choice, multi-response, True/False, clickable Hot spot, etc. types. It was tested exhaustively and saved many times.
On finally opening the source file, in ALL of the six multi-choice questions, the question 'object' had been moved from time zero on the timeline to exactly line up with the second audio file. This had never happened in earlier source versions and I have been unable to replicate the problem.
These two screen grabs show: one of the six questions before the error crept in and the other with the quiz object moved by SL3 to line up with the second audio.