baffling undefined method

I have a model

class Person < CimHrdb
  ...
  belongs_to :local_province, :foreign_key =>
"person_local_province_id", :class_name => "Province"
  ...
end

(where CimHrdb extends some classes (with abstract_class = true) that
eventually extend ActiveRecord::Base)

and I'm getting

A NoMethodError occurred in reports#crisis_management:

undefined method `local_province' for #<Person:0x40eec754>
[RAILS_ROOT]/vendor/rails/activerecord/lib/active_record/base.rb:
1799:in `method_missing'

The confusing thing is that it happens every once in a while. It's
not every time. I can't figure out why. It seems to not set up the
local_province method at times. This is on a production mongrel
server, btw.

-Andrew Roth

Just wanted to follow up on this. I found out that it's because one
of my log/mongrel.pid files got erased, so when mongrel was
restarting, it couldn't kill one of them. Then it kept running with
old classes loaded. So one of my three mongrels had old classes
loaded, explaining why it only happened sometimes.

-Andrew