Getting rid of ActionController::InvalidAuthenticityToken (Rails 3, webrick, devise)

Cannot figure this one out. Developing Rails 3.0.3 app using Devise 1.1.5, running locally on WEBrick 1.3.1. Out of nowhere I get a

ActionController::InvalidAuthenticityToken

error on login (successful or not) and registration. The app is deployed to Heroku, and works fine in production. It also works fine on another dev's machine, running on Apache/Passenger. No matter what I do I can't get rid of this error locally (and it ran fine several days ago until this error popped up mid-development).

I've checked out fresh code, restarted machine, run on different ports, wiped out db, everything I can think of. No caching in the app.

Application trace is blank. Full trace below:

actionpack (3.0.3) lib/action_controller/metal/request_forgery_protection.rb:96:in `verify_authenticity_token'
activesupport (3.0.3) lib/active_support/callbacks.rb:441:in `_run__2106070066__process_action__1623385099__callbacks'
activesupport (3.0.3) lib/active_support/callbacks.rb:409:in `send'
activesupport (3.0.3) lib/active_support/callbacks.rb:409:in `_run_process_action_callbacks'
activesupport (3.0.3) lib/active_support/callbacks.rb:93:in `send'
activesupport (3.0.3) lib/active_support/callbacks.rb:93:in `run_callbacks'
actionpack (3.0.3) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
activesupport (3.0.3) lib/active_support/notifications.rb:52:in `instrument'
activesupport (3.0.3) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (3.0.3) lib/active_support/notifications.rb:52:in `instrument'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/rescue.rb:17:in `process_action'
actionpack (3.0.3) lib/abstract_controller/base.rb:120:in `process'
actionpack (3.0.3) lib/abstract_controller/rendering.rb:40:in `process'
actionpack (3.0.3) lib/action_controller/metal.rb:138:in `dispatch'
actionpack (3.0.3) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.0.3) lib/action_controller/metal.rb:178:in `action'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:62:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:62:in `dispatch'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:27:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/mapper.rb:35:in `call'
rack-mount (0.6.13) lib/rack/mount/route_set.rb:148:in `call'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:93:in `recognize'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:68:in `optimized_each'
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:92:in `recognize'
rack-mount (0.6.13) lib/rack/mount/route_set.rb:139:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:492:in `call'
warden (1.0.3) lib/warden/manager.rb:35:in `call'
warden (1.0.3) lib/warden/manager.rb:34:in `catch'
warden (1.0.3) lib/warden/manager.rb:34:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/head.rb:14:in `call'
rack (1.2.1) lib/rack/methodoverride.rb:24:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/flash.rb:182:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/cookies.rb:295:in `call'
activerecord (3.0.3) lib/active_record/query_cache.rb:32:in `call'
activerecord (3.0.3) lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache'
activerecord (3.0.3) lib/active_record/query_cache.rb:12:in `cache'
activerecord (3.0.3) lib/active_record/query_cache.rb:31:in `call'
activerecord (3.0.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:353:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:46:开发者_运维知识库in `call'
activesupport (3.0.3) lib/active_support/callbacks.rb:415:in `_run_call_callbacks'
actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:44:in `call'
rack (1.2.1) lib/rack/sendfile.rb:107:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/show_exceptions.rb:46:in `call'
railties (3.0.3) lib/rails/rack/logger.rb:13:in `call'
rack (1.2.1) lib/rack/runtime.rb:17:in `call'
activesupport (3.0.3) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.2.1) lib/rack/lock.rb:11:in `call'
rack (1.2.1) lib/rack/lock.rb:11:in `synchronize'
rack (1.2.1) lib/rack/lock.rb:11:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/static.rb:30:in `call'
railties (3.0.3) lib/rails/application.rb:168:in `call'
railties (3.0.3) lib/rails/application.rb:77:in `send'
railties (3.0.3) lib/rails/application.rb:77:in `method_missing'
railties (3.0.3) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.2.1) lib/rack/content_length.rb:13:in `call'
rack (1.2.1) lib/rack/handler/webrick.rb:52:in `service'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/httpserver.rb:65:in `run'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:173:in `start_thread'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:162:in `start'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:162:in `start_thread'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:95:in `start'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:92:in `each'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:92:in `start'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:23:in `start'
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/webrick/server.rb:82:in `start'
rack (1.2.1) lib/rack/handler/webrick.rb:13:in `run'
rack (1.2.1) lib/rack/server.rb:213:in `start'
railties (3.0.3) lib/rails/commands/server.rb:65:in `start'
railties (3.0.3) lib/rails/commands.rb:30
railties (3.0.3) lib/rails/commands.rb:27:in `tap'
railties (3.0.3) lib/rails/commands.rb:27
script/rails:6:in `require'
script/rails:6

Any help is appreciated!

Edit: Here's the post from the log:

Started POST "/users/sign_in" for 127.0.0.1 at Thu Jan 13 11:04:43 -0700 2011
  Processing by Users::SessionsController#create as HTML
  Parameters: {"commit"=>"Sign in", "authenticity_token"=>"5R+ZYh3w/GiQwTdXExqj5O1u7Jkhrg2wclO1jfYvP5k=", "utf8"=>"✓", "user"=>{"remember_me"=>"0", "password"=>"[FILTERED]", "email"=>"jason.lynes@gmail.com"}}
Completed   in 1ms

ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken):

---

The other thing you might try is to add:

config.action_controller.allow_forgery_protection = false

into your development environment file.