Just one thing - what is with post date 1970?
You mean y'all can't remember all those posts you made at 1.00am on 1st January 1970. Aaaah I remember it well - such a busy time here on the forum. And then - years of silence until now, when we're surrounded with the busy clucks of chickens everywhere!
OK, err, the real answer is that the loss of the pre-upgrade dates was one of the expected glitches that seems to have been reported by loads of other boards who have tried upgrading. Sorry about that - I still have backups of all data before the upgrade so could try getting the dates put back in correctly at a later stage, but slightly scared of messing other stuff up after knowing how problematic the upgrade actually was. If everyone really wants the dates back I'll try to do it at some later stage when I can totally ensure there will be no complications.