Hey there, dcshaker.
Was there ever a case where some of the files which were able to play before, couldn't be played when you've tried them with a different combination of videos? If the files are always the same, perhaps they are corrupted, or if you're trying them with a TV, maybe there's an issue with it and I'd recommend that you contact the manufacturer's customer support and ask for further assistance. However, if you're trying them with a computer, I'd recommend that you try them with a different computer as well, to see if the same thing happens. Also try to write some vids with the other computer to see if they can be played properly.
Hope that helps. Please let me know how everything goes.
Boogieman_WD