I'm on Mac and happens to me once in a while also, more often lately. It rarely happens directly when I start the game, but after I've been playing for a while between songs, and it's never the same song that triggers it. Same for me it works if I disable the network, but songs are missing. I've been thinking it could be broken or conflicting CDLC songs, but I've not been able to find the cause, did you ever found out what caused your crashes?