I have the Blackvue DR650S-2CH and the other day, I was watching the files on my Mac and all of a sudden the video froze, then was ok, then froze.....very sporadic! The audio did the same. Wonder what caused that? Also, I was watching another video last night and while playing, the video seemed to change from 30fps, then 15fps, then back again. It did this several times. Any suggestions?