In marked contrast to the spam bot above me, I have found the solution. My files were too big, over the 4 GB limit of WAV files. I knew that there was a limit, I just thought that it will stand out much earlier, at the point of file creation.
Now I chopped the file down and had to fix them because of another problem with Premiere Pro:
http://mshg33.blogspot.de/2015/04/why-do-i-get-broken-wav-files-with.html