Yeeeee, un truco es pegar el error el google, te saldran cosas seguro
http://logic-users.org/forums/LUG/thread/79226
Parece ser una cosa de permisos de OSX, al usar wavs sacados de un CD grabado en PC ocosas similares..
La solución:
Menu FILE > get info.
Hay que seleccionar "read & write"
Go to "Get Info" from your FILE pulldown menu and check to see if your Privledges allow to to "read & write" or just "read". If the file is set to "Read Only" change it to "Read & Write" and everything will work fine. It's an OS X "permissions" thing.
Tb dicen que puedes probar a usar la herramienta de reparador de permisos, de las utilidades de disco.
You might also try using the Repair Permissions tool in the Apple Disk Utility (assuming you're using OS X).