When trying to play or download audio i kept getting a 404 (which drupal was reporting because it couldn't find 403.shtml (hosting default)) ... the reason being, i has specified my audio import directory as 'audio' which was in-conflict with the virtual-directory scheme used by the audio module.
Changing the permissions on the folder weren't enough. In my case i had to rename the directory to something else.

Took me about an hour to find this "bug" maybe a note on the audio upload page "don't use 'audio' " ??

-bruce