Bunch of errors after dropping module into folder

Just in case this might be of any help, I have a fresh D7.0 installation with only the following contrib modules:

• references (activated)
• views (not activated for know reason)
• ctools (not activated)

I added one role and 2 content types (w/ custom fields) for one of which I added 2 test nodes.
Refreshing the modules page, "I see red":

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'sites/all/modules/ctools/bulk_export/bulk_export.module' for key 'PRIMARY': INSERT INTO {system} (filename, name, type, owner, info) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4), (:db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9), (:db_insert_placeholder_10, :db_insert_placeholder_11, :db_insert_placeholder_12, :db_insert_placeholder_13, :db_insert_placeholder_14), (:db_insert_placeholder_15, :db_insert_placeholder_16, :db_insert_placeholder_17, :db_insert_placeholder_18, :db_insert_placeholder_19), (:db_insert_placeholder_20, :db_insert_placeholder_21, :db_insert_placeholder_22, :db_insert_placeholder_23, :db_insert_placeholder_24), (:db_insert_placeholder_25, :db_insert_placeholder_26, :db_insert_placeholder_27, :db_insert_placeholder_28, :db_insert_placeholder_29), (:db_insert_placeholder_30, :db_insert_placeholder_31, :db_insert_placeholder_32, :db_insert_placeholder_33, :db_insert_placeholder_34), (:db_insert_placeholder_35, :db_insert_placeholder_36, :db_insert_placeholder_37, :db_insert_placeholder_38, :db_insert_placeholder_39), (:db_insert_placeholder_40, :db_insert_placeholder_41, :db_insert_placeholder_42, :db_insert_placeholder_43, :db_insert_placeholder_44), (:db_insert_placeholder_45, :db_insert_placeholder_46, :db_insert_placeholder_47, :db_insert_placeholder_48, :db_insert_placeholder_49); Array ( [:db_insert_placeholder_0] => sites/all/modules/ctools/bulk_export/bulk_export.module [:db_insert_placeholder_1] => bulk_export [:db_insert_placeholder_2] => module [:db_insert_placeholder_3] => [:db_insert_placeholder_4] => a:11:{s:4:"name";s:11:"Bulk Export";s:11:"description";s:67:"Performs bulk exporting of data objects known about by Chaos tools.";s:4:"core";s:3:"7.x";s:12:"dependencies";a:1:{i:0;s:6:"ctools";}s:7:"package";s:16:"Chaos tool suite";s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:5:"files";a:0:{}s:9:"bootstrap";i:0;} [:db_insert_placeholder_5] => sites/all/modules/ctools/ctools.module [:db_insert_placeholder_6] => ctools [:db_insert_placeholder_7] => module [:db_insert_placeholder_8] => [:db_insert_placeholder_9] => a:11:{s:4:"name";s:11:"Chaos tools";s:11:"description";s:46:"A library of helpful tools by Merlin of Chaos.";s:4:"core";s:3:"7.x";s:7:"package";s:16:"Chaos tool suite";s:5:"files";a:3:{i:0;s:20:"includes/context.inc";i:1;s:22:"includes/math-expr.inc";i:2;s:21:"includes/stylizer.inc";}s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:12:"dependencies";a:0:{}s:3:"php";s:5:"5.2.4";s:9:"bootstrap";i:0;} [:db_insert_placeholder_10] => sites/all/modules/ctools/ctools_access_ruleset/ctools_access_ruleset.module [:db_insert_placeholder_11] => ctools_access_ruleset [:db_insert_placeholder_12] => module [:db_insert_placeholder_13] => [:db_insert_placeholder_14] => a:11:{s:4:"name";s:15:"Custom rulesets";s:11:"description";s:81:"Create custom, exportable, reusable access rulesets for applications like Panels.";s:4:"core";s:3:"7.x";s:7:"package";s:16:"Chaos tool suite";s:12:"dependencies";a:1:{i:0;s:6:"ctools";}s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:5:"files";a:0:{}s:9:"bootstrap";i:0;} [:db_insert_placeholder_15] => sites/all/modules/ctools/ctools_ajax_sample/ctools_ajax_sample.module [:db_insert_placeholder_16] => ctools_ajax_sample [:db_insert_placeholder_17] => module [:db_insert_placeholder_18] => [:db_insert_placeholder_19] => a:11:{s:4:"name";s:33:"Chaos Tools (CTools) AJAX Example";s:11:"description";s:41:"Shows how to use the power of Chaos AJAX.";s:7:"package";s:16:"Chaos tool suite";s:12:"dependencies";a:1:{i:0;s:6:"ctools";}s:4:"core";s:3:"7.x";s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:5:"files";a:0:{}s:9:"bootstrap";i:0;} [:db_insert_placeholder_20] => sites/all/modules/ctools/ctools_custom_content/ctools_custom_content.module [:db_insert_placeholder_21] => ctools_custom_content [:db_insert_placeholder_22] => module [:db_insert_placeholder_23] => [:db_insert_placeholder_24] => a:11:{s:4:"name";s:20:"Custom content panes";s:11:"description";s:79:"Create custom, exportable, reusable content panes for applications like Panels.";s:4:"core";s:3:"7.x";s:7:"package";s:16:"Chaos tool suite";s:12:"dependencies";a:1:{i:0;s:6:"ctools";}s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:5:"files";a:0:{}s:9:"bootstrap";i:0;} [:db_insert_placeholder_25] => sites/all/modules/ctools/ctools_plugin_example/ctools_plugin_example.module [:db_insert_placeholder_26] => ctools_plugin_example [:db_insert_placeholder_27] => module [:db_insert_placeholder_28] => [:db_insert_placeholder_29] => a:11:{s:4:"name";s:35:"Chaos Tools (CTools) Plugin Example";s:11:"description";s:75:"Shows how an external module can provide ctools plugins (for Panels, etc.).";s:7:"package";s:16:"Chaos tool suite";s:12:"dependencies";a:4:{i:0;s:6:"ctools";i:1;s:6:"panels";i:2;s:12:"page_manager";i:3;s:13:"advanced_help";}s:4:"core";s:3:"7.x";s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:5:"files";a:0:{}s:9:"bootstrap";i:0;} [:db_insert_placeholder_30] => sites/all/modules/ctools/tests/ctools_plugin_test.module [:db_insert_placeholder_31] => ctools_plugin_test [:db_insert_placeholder_32] => module [:db_insert_placeholder_33] => [:db_insert_placeholder_34] => a:12:{s:4:"name";s:24:"Chaos tools plugins test";s:11:"description";s:42:"Provides hooks for testing ctools plugins.";s:7:"package";s:16:"Chaos tool suite";s:4:"core";s:3:"7.x";s:12:"dependencies";a:1:{i:0;s:6:"ctools";}s:5:"files";a:2:{i:0;s:19:"ctools.plugins.test";i:1;s:17:"object_cache.test";}s:6:"hidden";b:1;s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:9:"bootstrap";i:0;} [:db_insert_placeholder_35] => sites/all/modules/ctools/page_manager/page_manager.module [:db_insert_placeholder_36] => page_manager [:db_insert_placeholder_37] => module [:db_insert_placeholder_38] => [:db_insert_placeholder_39] => a:11:{s:4:"name";s:12:"Page manager";s:11:"description";s:54:"Provides a UI and API to manage pages within the site.";s:4:"core";s:3:"7.x";s:12:"dependencies";a:1:{i:0;s:6:"ctools";}s:7:"package";s:16:"Chaos tool suite";s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:5:"files";a:0:{}s:9:"bootstrap";i:0;} [:db_insert_placeholder_40] => sites/all/modules/ctools/stylizer/stylizer.module [:db_insert_placeholder_41] => stylizer [:db_insert_placeholder_42] => module [:db_insert_placeholder_43] => [:db_insert_placeholder_44] => a:11:{s:4:"name";s:8:"Stylizer";s:11:"description";s:53:"Create custom styles for applications such as Panels.";s:4:"core";s:3:"7.x";s:7:"package";s:16:"Chaos tool suite";s:12:"dependencies";a:2:{i:0;s:6:"ctools";i:1;s:5:"color";}s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:5:"files";a:0:{}s:9:"bootstrap";i:0;} [:db_insert_placeholder_45] => sites/all/modules/ctools/views_content/views_content.module [:db_insert_placeholder_46] => views_content [:db_insert_placeholder_47] => module [:db_insert_placeholder_48] => [:db_insert_placeholder_49] => a:11:{s:4:"name";s:19:"Views content panes";s:11:"description";s:104:"Allows Views content to be used in Panels, Dashboard and other modules which use the CTools Content API.";s:7:"package";s:16:"Chaos tool suite";s:12:"dependencies";a:2:{i:0;s:6:"ctools";i:1;s:5:"views";}s:4:"core";s:3:"7.x";s:5:"files";a:3:{i:0;s:61:"plugins/views/views_content_plugin_display_ctools_context.inc";i:1;s:57:"plugins/views/views_content_plugin_display_panel_pane.inc";i:2;s:59:"plugins/views/views_content_plugin_style_ctools_context.inc";}s:7:"version";s:14:"7.x-1.0-alpha2";s:7:"project";s:6:"ctools";s:9:"datestamp";s:10:"1294276864";s:3:"php";s:5:"5.2.4";s:9:"bootstrap";i:0;} ) in system_update_files_database() (Zeile 2273 von D:\docroots\kiezbuerger\modules\system\system.module).

After a second try (clicked "Modules" instead of refreshing page) it went up in smoke.