Occational errors in XDCAMHD-exports from Macbooks

My company use the XDCAMHD 1080i50 codec in an .mxf wrapper as a delivery format. We use windows computers in the studio to edit and export material, and Macbook Pro for our people in the field. Using the same preset in Media Encoder as the windows computers, the Macbooks sometimes produce files with errors. They appear as lagging in the image in everything from half second blips one time during the whole file to lags once every 2-3 seconds throughout the file. On close inspection the "lags" are really frames playing in the wrong order. Example, it will play frame 4-1-2-3-8-5-6-7. The errors are inconsistent, but will only occur on Macbooks. You could get 4 good files from a machine and one bad. Several exports from the same machine using the same raw material will produce errors in different places in the file. Have anyone encountered this?