It's new and we had the first trouble ;-)
After we installed the new forum we had some problems with our MySql database and so the forum was unreachable because we had an overflow in one table.
Unfortunately it was the user table and I had to drop it to solve the problem.
All userdata, who had registered after upgrading the forums have been lost :-((.
The other userdata was save so you can use your account normally.
Only the brand new users have to register again. Sorry!