This one is pretty easy to fix. First, let me tell you why this happens with MC and not with other software:
When you try to play these files with MC, MC wants to give you the highest quality sound possible. So it tells your hardware to switch to the sample rate inside of your file. For example, when you play a 44.1kHz file, MC tells the hardware to switch to 44.1kHz. With other players, they resample the file on the fly, and just use whatever sample rate the hardware happens to be using.
So, when MC sees a file with a value that's not very typical (like 32kHz), it tells the hardware to switch to that value and the hardware can't do it because it's not supported. Your Mac's internal sound card should support 44.1, 48, 96, and possibly 88.2 kHz. But not 32kHz.
The solution is to use the DSP Studio > Output Format > Sample Rate section. Just tell it to map everything under 44.1 kHz to 96 kHz. While you're there, set everything *above* 96kHz to 96kHz also. That way if you try to play a VERY high sample rate file, MC will be able to convert it for you.
That should fix this issue for you.
Brian.