I get the same exact error. I also experienced it during the Beta, too. I found that if I leave the lobby after 1 round, then join another game with less than 35 seconds or so on the countdown timer (in the upper right), I would be able to join the next map. But as soon as I joined a game and the timer was more than say 40+ seconds left on the countdown, I would have this same error where it would REFUSE to load into the next map. It's REALLY annoying to have to exit a server and re-join another server hoping that you'll be joining near the start of a new round!
Please fix this or at least let us know what needs to be done to fix it!
