Thanks for your reply. The playback speeds in the control window are both at 29.97 as they should be, I have actually used the exact same show files, same settings on EVERYTHING.. still this issue persists I am not expecting them to run the same at all but it is clear that there is a large discrepancy that is related to mountain lion as I can switch over operating systems and things stay very close to in sync. I understand what you mean regarding the audio play mode.. that is why I used it to fix my problem for that show. The fact that the diference in play speed varies that much just changing to that play mode illustrates the problem. THe file is made @ 29.97, catalyst is set to play at 29.97, layer play speed at 100 percent, so changing to an audio play mode shouldnt cause much of a change... The reality is that its drastic. I will keep looking into it but I really think something is amiss. I have spent many hours on this and am not a stranger to catalyst. If there is any other info you wish to know please ask. Thanks