At 2016-oct-16, calendar goes back to 1970 (or, "cannot disable Tardis")
I'm having the same issue and I saw another post saying that it's happening due to the beginning of summer time in Brasil, in October 16, so if you change your timezone it should stop...
Obviously won't work for me because I live here and changing the timezone is not an option, but it's worth giving a try :) (even because the person that figured it out didn't say a thing about fixing it).
Cheers!