rMBP pause on video playback?

Hi. I recently purchased a rMBP 2.4Ghz Intel Core i7. During playback of .mkv, .avi and .mp4 files in full screen I get a pause or it can be described as a 'hang' in playback lasting one second every 40min to 1hr, im not referring to a drop of frame rate, just a slight pause and the file continues to play as if nothing happened. Now ive noticed this is random because if I rewind to the point where it paused for a second the movie continues to play without the pause. What im saying is I can't recreate the pause in playback. This happens using the latest versions of vlc and quicktime whilst no other apps are running in the background such as safari. The .mkv, .avi and mp4 files are stored on the rMBP internal ssd. Ive also turned off "put hard disks to sleep when possible" and ive put display and computer sleep to never in system preferences to see if it helps. Also i have turned off 'automatic graphic switching' so that I am using nvidia gfx and my ssd is 85% free. The problem is not the files themselves - my other desktop computer plays these files without any pauses.

Any ideas what might be causing these pauses in video playback, could it be my ssd?

Thx.