Imagine you're a member of a band popular enough to not only have a song included in a popular music video game but to have your likeness featured in the same game. Then imagine you fire the game up and discover that you can use your personal avatar to play along with any song in the game – including those sung by men.
This is the problem that No Doubt's Gwen Stefani came across when she played the game for the first time, and it's what led to the lawsuit. Although Activision tried to have the claim dismissed last year, the whole thing will start to be sorted on October 15th.
This was one of a number of complaints issued against Activision over the last couple of Guitar Hero games. It certainly gives an idea as to why the series might have been shelved for a while. Thankfully, Rock Band is still up and running, releasing weekly DLC and completely failing to embarrass, alienate or piss off the artists working with them.