Rails 3, MongoId & bson version problem

I just updated to Rails 3 final. Now I'm having problems with MongoId, Mongo's Ruby driver & bson. When I try to run Rails, I get "You have already activated bson 1.0.7, but your Gemfile requires bson 1.0.4. Consider using bundle exec. (Gem::LoadError)".

MongoId requires bson_ext 1.0.4 so I have开发者_高级运维 gem "bson_ext", "1.0.4" in my Gemfile. I tried to uninstall bson 1.0.7 but then Rails failed to start because Mongo Ruby driver requires bson >= 1.0.5.

So any ideas how I can get this solved?

this combination works for me:

gem 'rails',     '3.0.6'
gem "mongoid",   "2.0.0"
gem "bson",      "1.2.4"
gem "bson_ext",  "1.2.4"

gem "devise" ,   "1.1.6"