Installation Error Re Cake

[jconsole21]

Fatal error: Uncaught Error: Class 'String' not found in /usr/share/php/Cake/Model/Datasource/DboSource.php:2487 Stack trace: #0 /usr/share/php/Cake/Model/Datasource/DboSource.php(1585): DboSource->fields(Object(Page), 'Page', 'Page.id') #1 /usr/share/php/Cake/Model/Datasource/DboSource.php(1613): DboSource->prepareFields(Object(Page), Array) #2 /usr/share/php/Cake/Model/Datasource/DboSource.php(1102): DboSource->buildAssociationQuery(Object(Page), Array) #3 /usr/share/php/Cake/Model/Model.php(2950): DboSource->read(Object(Page), Array) #4 /usr/share/php/Cake/Model/Model.php(2922): Model->_readDataSource('all', Array) #5 /home/ubuntu/rms/app/Controller/AppController.php(74): Model->find('all', Array) #6 /usr/share/php/Cake/Event/CakeEventManager.php(243): AppController->beforeFilter(Object(CakeEvent)) #7 /usr/share/php/Cake/Controller/Controller.php(676): CakeEventManager->dispatch(Object(CakeEvent)) #8 /usr/share/php/Cake/Error/ExceptionRenderer.php(155): Controller->startupProcess() #9 /usr/share/php/Cake/Error/Exceptio in /usr/share/php/Cake/Model/Datasource/DboSource.php on line 2487