When I access the 'admin/build/context' configuration form, only the 'admin/build' page is served. But if I enable the recommended (NB: NOT required) module Admin (6.x-2.0) and next disable, uninstall and remove that module, the form becomes normally accessible and usable. This issue occurs with both 3.0 and 3.x dev.

BTW: IMO the Admin module (http://drupal.org/project/admin) should not become required (merely recommended).