Trouble with QT files being out of synch when played back on iMac Retina

I just got a new iMac Retina and have hit a problem I've never encountered before. When I produce a standard QT file on my macbook pro, it plays fine (the audio is in synch with the video), but when I copy that same file to my new iMac Retina and play it there, there is a MAJOR synch problem. The video starts playing and there is no sound for @ 1 1/2 seconds, then the sound starts at the beginning of the file (so it is @ 1 1/2 second slower than the video and remains out of synch for as long as you play the file. What could be causing this?

Running OS X 10.11.3 on both machines.