from the download site:
To protect your MP3 files
1. Before you install this Beta release, back up all MP3 files that might be accessed by the computer, including those on removable media or network shares.
I guess it's for granted that you should back up your files when installing an operating system, but to admit that it's possibly going to do something nasty to one particular file format really ticks me off somewhat.
Wow! I agree with you NickFnord that's kinda crappy of Microsoft to possibly be targeting a single format. And to be aggressive enough to affect even files stored on share drives is a bit over the top. I am definitely going to have to play around with this little "feature".