Your log file suggests that the music folders you set up (Z:\music) does not exist. I'm sure they do exist but perhaps these are shared "parallels" folders which MeCanto is having trouble accessing.
My suggestions:
Try copying some music files to a folder inside the Windows virtual machine and adding that folder to MeCanto (instead of using a parallels shared folder). This won't solve the problem but it'll help us understand if this is related to parallels or not. Once done let us know if MeCanto finds those files.
Try installing our beta version for Mac ( available on http://mecanto.com/download ). Let us know if this works. If it does then you're better off using it instead of running MeCanto under parallels.