Hi, the simplest way I've found is here http://forum.xda-developers.com/showthread.php?p=42116378
. You do have to be rooted with a custom recovery I'm afraid, but does the trick just by flashing the zip in your custom recovery.
Sorry, don't know the solution to your problem, but all mp3s on my sd card working fine after rooting and flashing this, without corruption, so keep trying!!