Sony maliciously tampers with it's clients personal computers.
BBC NEWS | Technology | The rootkit of all evil?
: "The software, called Extended Copy Protection or XCP, hides itself on your hard drive using techniques normally reserved for viruses, worms and trojans, which use similar 'rootkits' to evade detection.
And if you notice it is there and try to remove it you may stop your computer recognising its CD drive.
This is because the cloaking techniques involve making changes to the Windows registry, altering the way device drivers work and generally messing with your installation."