Apparently, some new Sony CDs contain DRM software that hides files just like a rootkit. The post itself is pretty much the process of digging up the stuff it put on the guy’s computer, and the process of eliminating it. It’s not mentioned in the CD’s EULA. Also, unless you remove it the exact right way, you’ll cripple your computer, yay.
The point is, this behavior is the sort of thing usually only done by spyware and viruses, and even ignoring anything the DRM itself does, the rootkit could easily be exploited by other malware writers - hey, just start your filenames with a “$sys$” and no one who’s played Sony CDs on their computer will see them!
All the more reason to download music from the internet. And I’m even one of the people who usually does buy my CDs.