These do sound like corupt/faulty/fake files, especially since you say they are reading 20 mins for a file, as this time length would indicate a file of 20 MB or more. ...althought sound might be the wrong word to use lol
What media player are you using? are these mp3 files? ..if not what type are they ..... also I suggest downloading some random files which look ok and see what happens with them. You can always delete them if not to your taste. If you want to give more details of the files .. which should not be given on the forums ..please feel free pm me. (button below)