crash when trying to define an event

http://mysite.ca/civicrm/admin/event - after submitting page to define a new event

unrecoverable error
Sorry. A non-recoverable error has occurred.

Database Error Code: Cannot add or update a child row: a foreign key constraint fails (`csi_civ/civicrm_log`, CONSTRAINT `FK_civicrm_log_modified_id` FOREIGN KEY (`modified_id`) REFERENCES `civicrm_contact` (`id`) ON DELETE CASCADE), 1452

Return to home page.

Here's the details below that and the backtrace:
Error Details:

Array
(
[callback] => Array
(
[0] => CRM_Core_Error
[1] => handle
)

[code] => -1
[message] => DB Error: unknown error
[mode] => 16
[debug_info] => INSERT INTO civicrm_log (entity_table , entity_id , modified_id , modified_date ) VALUES ('civicrm_event' , 1 , 104 , 20080416 ) [nativecode=1452 ** Cannot add or update a child row: a foreign key constraint fails (`csi_civ/civicrm_log`, CONSTRAINT `FK_civicrm_log_modified_id` FOREIGN KEY (`modified_id`) REFERENCES `civicrm_contact` (`id`) ON DELETE CASCADE)]
[type] => DB_Error
[user_info] => INSERT INTO civicrm_log (entity_table , entity_id , modified_id , modified_date ) VALUES ('civicrm_event' , 1 , 104 , 20080416 ) [nativecode=1452 ** Cannot add or update a child row: a foreign key constraint fails (`csi_civ/civicrm_log`, CONSTRAINT `FK_civicrm_log_modified_id` FOREIGN KEY (`modified_id`) REFERENCES `civicrm_contact` (`id`) ON DELETE CASCADE)]
[to_string] => [db_error: message="DB Error: unknown error" code=-1 mode=callback callback=CRM_Core_Error::handle prefix="" info="INSERT INTO civicrm_log (entity_table , entity_id , modified_id , modified_date ) VALUES ('civicrm_event' , 1 , 104 , 20080416 ) [nativecode=1452 ** Cannot add or update a child row: a foreign key constraint fails (`csi_civ/civicrm_log`, CONSTRAINT `FK_civicrm_log_modified_id` FOREIGN KEY (`modified_id`) REFERENCES `civicrm_contact` (`id`) ON DELETE CASCADE)]"]
)

backTrace

/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/Error.php, backtrace, 148
, handle,
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/PEAR.php, call_user_func, 901
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/DB.php, PEAR_Error, 888
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/PEAR.php, DB_Error, 563
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/DB/common.php, raiseError, 1849
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/DB/mysql.php, raiseError, 894
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/DB/mysql.php, mysqlRaiseError, 324
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/DB/common.php, simpleQuery, 1162
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/DB/DataObject.php, query, 2343
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/DB/DataObject.php, _query, 1033
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/DAO.php, insert, 248
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/BAO/Log.php, save, 80
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Event/BAO/Event.php, add, 161
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Event/Form/ManageEvent/EventInfo.php, create, 273
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/StateMachine.php, postProcess, 166
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/QuickForm/Action/Next.php, perform, 63
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/HTML/QuickForm/Controller.php, perform, 195
/home/cividrupal/htdocs/sites/all/modules/civicrm/packages/HTML/QuickForm/Page.php, handle, 95
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/Controller.php, handle, 223
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Event/Page/ManageEvent.php, run, 157
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Event/Invoke.php, run, 56
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/Component.php, admin, 130
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/Invoke.php, invoke, 748
/home/cividrupal/htdocs/sites/all/modules/civicrm/CRM/Core/Invoke.php, admin, 102
/home/cividrupal/htdocs/sites/all/modules/civicrm/drupal/civicrm.module, invoke, 329
, civicrm_invoke,
/home/cividrupal/htdocs/includes/menu.inc, call_user_func_array, 418
/home/cividrupal/htdocs/index.php, menu_execute_active_handler, 15