Reindex error

exception 'Zend_Db_Statement_Exception' with message 'SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '512723-1-1' for key 'PRIMARY'' in /var/www/releases/20130211085532-v3.6.1/lib/Zend/Db/Statement/Pdo.php:242
Stack trace:
#0 /var/www/releases/20130211085532-v3.6.1/lib/Zend/Db/Statement.php(300): Zend_Db_Statement_Pdo->_execute(Array)
#1 /var/www/releases/20130211085532-v3.6.1/lib/Zend/Db/Adapter/Abstract.php(468): Zend_Db_Statement->execute(Array)
#2 /var/www/releases/20130211085532-v3.6.1/lib/Zend/Db/Adapter/Pdo/Abstract.php(238): Zend_Db_Adapter_Abstract->query('INSERT INTO cat...', Array)
#3 /var/www/releases/20130211085532-v3.6.1/lib/Varien/Db/Adapter/Pdo/Mysql.php(335): Zend_Db_Adapter_Pdo_Abstract->query('INSERT INTO cat...', Array)
#4 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/Index/Model/Mysql4/Abstract.php(159): Varien_Db_Adapter_Pdo_Mysql->query('INSERT INTO cat...')
#5 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/Index/Model/Mysql4/Abstract.php(134): Mage_Index_Model_Mysql4_Abstract->insertFromSelect('SELECT * FROM c...', 'cataloginventor...', Array, false)
#6 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/Index/Model/Mysql4/Abstract.php(88): Mage_Index_Model_Mysql4_Abstract->insertFromTable('cataloginventor...', 'cataloginventor...', false)
#7 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/CatalogInventory/Model/Mysql4/Indexer/Stock.php(262): Mage_Index_Model_Mysql4_Abstract->syncData()
#8 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/Index/Model/Indexer/Abstract.php(125): Mage_CatalogInventory_Model_Mysql4_Indexer_Stock->reindexAll()
#9 /var/www/releases/20130211085532-v3.6.1/app/code/local/Smile/Varnish/Model/Process.php(21): Mage_Index_Model_Indexer_Abstract->reindexAll()
#10 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/Index/Model/Process.php(167): Smile_Varnish_Model_Process->reindexAll()
#11 /var/www/releases/20130211085532-v3.6.1/shell/imports/products/import.php(177): Mage_Index_Model_Process->reindexEverything()
#12 /var/www/releases/20130211085532-v3.6.1/shell/imports/products/import.php(151): Mage_Shell_Products_Import->reindex('import_short.lo...')
#13 /var/www/releases/20130211085532-v3.6.1/app/code/local/Smile/ProductImport/Model/Observer.php(10): Mage_Shell_Products_Import->run()
#14 [internal function]: Smile_ProductImport_Model_Observer->runExport(Object(Mage_Cron_Model_Schedule))
#15 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/Cron/Model/Observer.php(105): call_user_func_array(Array, Array)
#16 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/Core/Model/App.php(1230): Mage_Cron_Model_Observer->dispatch(Object(Varien_Event_Observer))
#17 /var/www/releases/20130211085532-v3.6.1/app/code/core/Mage/Core/Model/App.php(1211): Mage_Core_Model_App->_callObserverMethod(Object(Mage_Cron_Model_Observer), 'dispatch', Object(Varien_Event_Observer))
#18 /var/www/releases/20130211085532-v3.6.1/app/Mage.php(430): Mage_Core_Model_App->dispatchEvent('default', Array)
#19 /var/www/releases/20130211085532-v3.6.1/cron.php(44): Mage::dispatchEvent('default')