Sony BMG temporarily suspend production of CDs containing the First4InternetXCP content protection. The technology employed by Sony to protect its music from illegitimate use was picked up by security software as a rootkit which hid files from Windows and made them impossible to detect. Simply using letters ‘$sys$’ in a file means that any such file will be hidden, even malicious files. Sony has distributed a patch to all anti-virus manufacturers to protect against this specific type of virus, so update those definitions kids and don’t let the man get you down.”]
Source: https://gizmodo.com/sony-stops-production-of-content-protection-cds-136847