On her Twitter page she said:
For the record this Guitar Hero shit is breach of contract on a Bullys part and there will be a proper addressing of this and retraction. We are going to sue the shit out of ACtivision we being the Trust the Estate the LLC the various LLCs Cobain Enterprises.
Activision's vice president Tim Riley had discussed how Courtney Love, Dave Grohl and Universal publishing had together signed a deal securing Cobain's appearance in the popular game, with the tracks "Smells Like Teen Spirit" and "Lithium" to be included. Riley even claimed that Love had herself been involved in the creation of the virtual Cobain.
Update: Activision has responded saying:
Guitar Hero secured the necessary licensing rights from the Cobain estate in a written agreement signed by Courtney Love to use Kurt Cobain's likeness as a fully playable character in Guitar Hero 5.