ArgumentError - AuthenticatedSystem

Any idea what would cause this error and how to fix it? It might be
caused by trying to access the server concurrently with the same user.
I found a reference to a similar bug but it should have already been
fixed. I'm using rails 1.2.2.

ArgumentError (A copy of AuthenticatedSystem has been removed from the
module tree but is still active!):
    C:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/
active_support/dependencies.rb:237:in `load_missing_constant'
    C:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/
active_support/dependencies.rb:452:in `const_missing'
    /lib/authenticated_system.rb:11:in `current_user'
    /lib/authenticated_system.rb:6:in `logged_in?'
    /lib/authenticated_system.rb:53:in `login_required'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/filters.rb:456:in `call'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/filters.rb:435:in `call'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/filters.rb:637:in `call_filter'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/filters.rb:619:in `perform_action_without_benchmark'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/benchmarking.rb:66:in
`perform_action_without_rescue'
    C:/ruby/lib/ruby/1.8/benchmark.rb:293:in `measure'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/benchmarking.rb:66:in
`perform_action_without_rescue'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/rescue.rb:83:in `perform_action'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/base.rb:430:in `process_without_filters'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/filters.rb:624:in
`process_without_session_management_support'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/session_management.rb:114:in `process'
    C:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/
action_controller/base.rb:330:in `process'
    C:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.2/lib/dispatcher.rb:41:in
`dispatch'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/mongrel/
rails.rb:78:in `process'
    C:/ruby/lib/ruby/1.8/thread.rb:135:in `synchronize'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/mongrel/
rails.rb:76:in `process'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/
mongrel.rb:618:in `process_client'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/
mongrel.rb:617:in `process_client'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/
mongrel.rb:736:in `run'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/
mongrel.rb:736:in `run'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/
mongrel.rb:720:in `run'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/mongrel/
configurator.rb:271:in `run'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/mongrel/
configurator.rb:270:in `run'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/bin/
mongrel_rails:127:in `run'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/lib/mongrel/
command.rb:211:in `run'
    C:/ruby/lib/ruby/gems/1.8/gems/mongrel-1.0.1-mswin32/bin/
mongrel_rails:243
    C:\ruby\bin\mongrel_rails:18
    -e:3