AssociationTypeMismatch / Model Caching in development envirnment

Hi there—

I'm trying to get started with Rails, and I've run into this issue and searched high and low--so hopefully someone can help point me in the right direction.

I'm having an issue where my model classes seem to be getting cached by something, and so if I make subsequent requests, I get an AssociationTypeMismatch error. To be specific, on update is where it fails, and I get:

ActiveRecord::AssociationTypeMismatch in ArticlesController#update Category(#2159283720) expected, got Category(#2154954600)

So sometimes this is successful, and the POST requests are identical.

I can change the 'config.cache_classes = false' to true in the config/environments/development to true and i won't get the error anymore, but then I have to reload the server every time I make a change.

I read that plugins could be caching it since they don't reload for every request, but I don't think I'm using any plugins, so I'm guessing that isn't it.

I can't figure out where to look next and would appreciate any help you can offer.

I'm running Ruby 1.9.2p0 and Rails 3.0.1 on OS X 10.6.4. You can download the code that I'm trying to work on at (I'm trying to work through this Apress book). When you load up the page, you need to log in to edit, and the login is '' : 'guessit'.

Any pointers or ideas?