Weird time class problem

I have a *huge* rails application here, and it fails when running tests and I really don't know why. Everything started after putting rails 1.1.6 in vendor/ but still, the error doesn't make any sense to me, and it doesn't give me enough informations to try to track the problem in the source code.

ngw@adreadedsunnyday ~/projects/hotchalk$ rake test --trace (in /Users/ngw/projects/hotchalk) ** Invoke test (first_time) ** Execute test ** Invoke test:units (first_time) ** Invoke db:test:prepare (first_time) ** Invoke environment (first_time) ** Execute environment ** Execute db:test:prepare ** Invoke db:test:clone_structure (first_time) ** Invoke db:structure:dump (first_time) ** Invoke environment ** Execute db:structure:dump ** Invoke db:test:purge (first_time) ** Invoke environment ** Execute db:test:purge ** Execute db:test:clone_structure ** Execute test:units /opt/local/bin/ruby -Ilib:test "/opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb" "test/unit/alert_notification_test.rb" "test/unit/alert_test.rb" "test/unit/assignment_person_answer_test.rb" "test/unit/assignment_person_submission_test.rb" "test/unit/assignment_person_test.rb" "test/unit/assignment_schedule_test.rb" "test/unit/assignment_test.rb" "test/unit/attendance_test.rb" "test/unit/calendar_test.rb" "test/unit/category_test.rb" "test/unit/content_test.rb" "test/unit/event_test.rb" "test/unit/grade_test.rb" "test/unit/group_member_test.rb" "test/unit/lesson_plan_metadata_test.rb" "test/unit/lesson_plan_schedule_test.rb" "test/unit/lesson_plan_test.rb" "test/unit/local_file_store_test.rb" "test/unit/localization_test.rb" "test/unit/message_test.rb" "test/unit/parent_invitation_test.rb" "test/unit/person_test.rb" "test/unit/prodev_courses_test.rb" "test/unit/prodev_subscriptions_test.rb" "test/unit/publisher_test.rb" "test/unit/resource_folder_test.rb" "test/unit/resource_question_test.rb" "test/unit/resource_test.rb" "test/unit/school_test.rb" "test/unit/server_test.rb" "test/unit/subject_privilege_test.rb" "test/unit/subject_roster_test.rb" "test/unit/subject_schedule_resource_test.rb" "test/unit/subject_schedule_test.rb" "test/unit/subject_test.rb" "test/unit/subject_textbook_test.rb" "test/unit/transaction_test.rb" /opt/local/lib/ruby/site_ruby/1.8/rubygems/source_index.rb:92:in `load_specification': undefined method `parse' for Time:Class (NoMethodError)          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:314:in `date='          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:416:in `send'          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:416:in `initialize'          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:412:in `each'          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:412:in `initialize'          from (eval):1:in `new'          from (eval):1:in `load_specification'          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/source_index.rb:128:in `eval'           ... 36 levels...          from /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb:5:in `load'          from /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb:5          from /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb:5:in `each'          from /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb:5 ** Invoke test:functionals (first_time) ** Invoke db:test:prepare ** Execute test:functionals /opt/local/bin/ruby -Ilib:test "/opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb" "test/functional/admin_controller_test.rb" "test/functional/backend_api_test.rb" "test/functional/parents_controller_test.rb" "test/functional/public_controller_test.rb" "test/functional/register_controller_test.rb" "test/functional/resources_controller_test.rb" "test/functional/send_alerts_test.rb" "test/functional/session_verifier_api_test.rb" "test/functional/shared_controller_test.rb" "test/functional/student_controller_test.rb" "test/functional/super_controller_test.rb" "test/functional/teachers_controller_assignments_test.rb" "test/functional/teachers_controller_test.rb" "test/functional/user_controller_test.rb" /opt/local/lib/ruby/site_ruby/1.8/rubygems/source_index.rb:92:in `load_specification': undefined method `parse' for Time:Class (NoMethodError)          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:314:in `date='          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:416:in `send'          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:416:in `initialize'          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:412:in `each'          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/specification.rb:412:in `initialize'          from (eval):1:in `new'          from (eval):1:in `load_specification'          from /opt/local/lib/ruby/site_ruby/1.8/rubygems/source_index.rb:128:in `eval'           ... 36 levels...          from /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb:5:in `load'          from /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb:5          from /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb:5:in `each'          from /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb:5 ** Invoke test:integration (first_time) ** Invoke db:test:prepare ** Execute test:integration /opt/local/bin/ruby -Ilib:test "/opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake/rake_test_loader.rb" rake aborted! Test failures /Users/ngw/projects/hotchalk/config/../vendor/rails/railties/lib/tasks/testing.rake:35 /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:387:in `call' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:387:in `execute' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:387:in `each' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:387:in `execute' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:357:in `invoke' /opt/local/lib/ruby/1.8/thread.rb:135:in `synchronize' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:350:in `invoke' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:1906:in `run' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:1906:in `each' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/lib/rake.rb:1906:in `run' /opt/local/lib/ruby/gems/1.8/gems/rake-0.7.1/bin/rake:7 /opt/local/bin/rake:16:in `load' /opt/local/bin/rake:16

where can I look ? ...

   ngw