Found a solution for the mac users. First let steam update and DON?T close it. Then disable wifi, enter time machine, chose yesterday, and search rocksmith on finder. You'll find an app located in a Steam folder, restore it, and you'll get the last available version that runs. As next time that Steam starts, probably will update again, it would be a good idea to put this version in a folder beside Rocksmith app. Just in case, if you add new CDLC, you should add both the functional Rocksmith and the security one in the folder, so if Steam update the new one, and you copy again the old one, it will be yet with the CDLC. Maybe it's not a very good solution, but at least it works.