associations don't load after upgrading to 1.2RC1

Hi,
My application runs fine on 1.1.6 but when i upgrade to 1.2 ( I need
1.2 for multibyte ), all my associations break..none of the acts_as
associations works any more - i'm using acts_as_taggable and
acts_as_commentable and i get errors like "undefined method 'tags' for
#<objectid>".

Even my :belongs_to association doesn't load anymore !

Do i need to do something special to load my associations in RC1.2?

Any help would be appreciated - thanks,
Temo