I had also this problem that Rocksmith didn't start at all. I don't remember exactly how I fixed it, but something like, going back one version, and I think I opted out of the betatesting versions too... I remember I copied the whole directory with the old refreshed version, in case the program would not function in the future, I maybe copied the refreshed old contents back after I upgraded the program, not sure though. But you can always search the forums on steam for more precise answer...