The following error appears when clicking on the check data integrity icon in the LS admin interface of the demo server (http://demo.limesurvey.org)

Couldn't make backup of the survey table. Please try again. The database reported the following error:
exception 'CDbException' with message 'CDbCommand failed to execute the SQL statement: SQLSTATE[HY000]: General error: 1017 Can't find file: './c1demo/lime_survey_114433.frm' (errno: 2)' in /var/www/clients/client1/web19/web/framework/db/CDbCommand.php:358 Stack trace: #0 /var/www/clients/client1/web19/web/framework/db/CDbCommand.php(1336): CDbCommand->execute() #1 /var/www/clients/client1/web19/web/application/controllers/admin/checkintegrity.php(382): CDbCommand->renameTable('{{survey_114433...', '{{old_survey_11...') #2 /var/www/clients/client1/web19/web/application/controllers/admin/checkintegrity.php(41): CheckIntegrity->_checkintegrity() #3 [internal function]: CheckIntegrity->index() #4 /var/www/clients/client1/web19/web/framework/web/actions/CAction.php(108): ReflectionMethod->invokeArgs(Object(CheckIntegrity), Array) #5 /var/www/clients/client1/web19/web/application/core/Survey_Common_Action.php(99): CAction->runWithParamsInternal(Object(CheckIntegrity), Object(ReflectionMethod), Array) #6 /var/www/clients/client1/web19/web/framework/web/CController.php(308): Survey_Common_Action->runWithParams(Array) #7 /var/www/clients/client1/web19/web/framework/web/CController.php(286): CController->runAction(Object(CheckIntegrity)) #8 /var/www/clients/client1/web19/web/framework/web/CController.php(265): CController->runActionWithFilters(Object(CheckIntegrity), Array) #9 /var/www/clients/client1/web19/web/application/controllers/AdminController.php(169): CController->run('checkintegrity') #10 /var/www/clients/client1/web19/web/framework/web/CWebApplication.php(282): AdminController->run('checkintegrity') #11 /var/www/clients/client1/web19/web/framework/web/CWebApplication.php(141): CWebApplication->runController('admin/checkinte...') #12 /var/www/clients/client1/web19/web/framework/base/CApplication.php(180): CWebApplication->processRequest() #13 /var/www/clients/client1/web19/web/index.php(200): CApplication->run() #14 {main}