Redmine

I've been trying to configure LDAP to work with our AD server. I installed a plugin for LDAP that didn't work out so I removed it. Now when I attempt to go into the LDAP settings under Administration I get an Internal error and this shows in the logs:

Processing by AuthSourcesController#index as HTML
  Current user: ctw (id=3)
Completed 500 Internal Server Error in 19.1ms

ActiveRecord::SubclassNotFound (The single-table inheritance mechanism failed to locate the subclass: 'AuthSourceLdapAdvanced'. This error is raised because the column 'type' is reserved for storing the class in case of inheritance. Please rename this column if you didn't intend it to be used for storing the inheritance class or overwrite AuthSource.inheritance_column to use another column for that information.):
  lib/redmine/pagination.rb:127:in `paginate'
  app/controllers/auth_sources_controller.rb:26:in `index'

When I do a db import I get no errors, and bundle install gives no errors. Not sure how to restore my settings as they were previously.

Environment:
  Redmine version                2.5.1.stable
  Ruby version                   1.9.3-p545 (2014-02-24) [i686-linux]
  Rails version                  3.2.17
  Environment                    production
  Database adapter               Mysql2
SCM:
  Subversion                     1.6.11
  Git                            1.7.1
  Filesystem
Redmine plugins:
  clipboard_image_paste          1.8
  projects_tree_view             0.0.8
  quick_view                     0.0.3
  redmine_contacts               3.2.17
  redmine_contacts_invoices      3.1.4
  redmine_custom_workflows       0.0.4
  redmine_dmsf                   1.4.8 stable
  redmine_improved_searchbox     0.0.3
  redmine_knowledgebase          3.0.4
  redmine_logs                   0.0.5
  redmine_monitoring_controlling 0.1.1
  redmine_people                 0.1.8
  redmine_silencer               0.4.0
  redmine_zenedit                0.0.2
  unread_issues                  0.0.1