Problem importing some tracks

Having an issue importing some tracks - either dragging them from iTunes or Windows Explorer. Traktor throws up the "missing, corrupt or DRM-protected file". The file is none of these things - it's an mp3 so no DRM and it's definitely there because I can play it in iTunes or VLC or Mixedinkey.

edit with a little more info: there are some tracks in my library that also won't load. these don't show up as problematic when I 'check consistency' of my library.

It might be worth mentioning that I recently reinstalled windows on my laptop and moved all my music and Traktor files over. It's not all tracks only some. I can't see any patterns in tracks that do work and tracks that don't.

happy edit: so I finally realised that the tracks were all m4a tracks and apparently you need quicktime installed to play them in traktor and apparently iTunes doesn't come with quicktime these days. So I installed quicktime and now it works. so you can close the thread if necessary