At Heise, there is a report about the problems with Sony BMG's copy protection:
This software emulates rootkit functions - rootkits also hide their (illegal) activities from the computer user. The copy protection installs filter drivers for CD-ROM drives and IDE drivers, through which it controls access to media.
Ultimately, this is another breach of user data integrity. And considering the idiotic copy protection laws in Germany, you're not even allowed to do anything about it. And so, the individual's right to their property (this is not just about Sony's silly CD, the entire computer is affected!) is once again sacrificed on the altar of the music industry's arrogance.
By the way, this copy protection also includes monitoring functions for media other than its own protected content - and in my opinion, this massively violates data protection regulations, because regardless of what Sony wants to protect, what else is going on on the computer is none of their business.
Another reason not to buy CDs from Sony BMG.