I uploaded one of the corrupted AAC music files to http://s000.tinyupload.com/?file_id=66772267805723556195
I hope this will give you the information you need.
Thank you for uploading the file!
I threw 3 different players using wasapi-exclusive at it, and every one shows a sudden stop around 30 seconds before the "end." MusicBee produced no strange noises, just a clean break like the others. Spek.exe shows a spectrogram with the waveform cutting off at the same time. This is a corrupted file, as phred observed, displaying the same results in any player.
How the file(s) initially became corrupted is anybody's guess, but my own is from an incomplete download when the file was initially acquired.
So it's not MusicBee's fault, but I'm sorry you ended up with them. If I were you I would see if you can re-download them from iTunes, there must be some kind of option for that if you paid for but received incomplete files.