This shouldn't even be an issue, but it has become one. . . Thanks Apple. . .
Since OS10.4.9, Apple has decided to change the byte order of their aiff files from big endian to little endian. These new 'aiff' files are really AIFF-C/sowt, but all you see is 'aiff' making it hard to determine which you have. Some programs use the old aiff format and some use the new 'aiff' format. Due to this issue, depending on your computer, you may or may not be able to read aiff files consistently. My advice is to abandon ship and stick to .wav files for all uses.