ActiveRecord::AssociationTypeMismatch (User(#54754560) expected, got User(#54510280))

i keep getting this AssociationTypeMismatch error. i think this could
be a bug related to ruby/rails when using mixins. heres a short
version of my code:

# user.rb

require 'friend_invitation'
require 'friendship'

class User < ActiveRecord::Base
  include FriendInvitationUser, FriendshipUser

  ...
end

# friendship.rb

...

module FriendshipUser
  def self.included(includer)
    includer.class_eval do
      has_many :friends, :through => :friendship
    end
  end

  # true, if other_user is a friend of mine
  def friend_of?(other_user)
    Friendship.between?(self, other_user)
  end

  ...
end

so basically I'm using modules to mixin new aspects into the User
model (kinda like AOP in ruby). i believe that these mixins together
with the require statements at the top of the User model file cause
the AssociationTypeMismatch. if i get the error, a restart of my
development server solves the problem - but that can't be the
solution. any ideas where this error comes from or what to do about
it?

any help very appreciated!

matthias

i keep getting this AssociationTypeMismatch error. i think this could
be a bug related to ruby/rails when using mixins. heres a short
version of my code:

# user.rb

require 'friend_invitation'
require 'friendship'

using require like this can bust stuff (see http://www.spacevatican.org/2008/9/28/required-or-not
  )

Fred

thanks for the link! it solved my problem :)! thank you so much!

matthias