Admin Panel & Store missing after enable System->Tools->Compilation

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http://magento.cybertoads.net/etiz/index.php/admin/

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Error message is:

There has been an error processing your request

Mage registry key "_singleton/flagbit_changeattributeset/observer" already exists

Trace:
#0 /home/onemelak/public_html/magento/etiz/app/Mage.php(222): Mage::throwException(‘Mage registry k…’)
#1 /home/onemelak/public_html/magento/etiz/app/Mage.php(476): Mage::register(‘_singleton/flag…’, false)
#2 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(21023): Mage::getSingleton(‘flagbit_changea…’)
#3 /home/onemelak/public_html/magento/etiz/app/Mage.php(447): Mage_Core_Model_App->dispatchEvent(‘adminhtml_block…’, Array)
#4 /home/onemelak/public_html/magento/etiz/includes/src/Mage_Adminhtml_Block_Template.php(80): Mage::dispatchEvent(‘adminhtml_block…’, Array)
#5 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(2518): Mage_Adminhtml_Block_Template->_toHtml()
#6 /home/onemelak/public_html/magento/etiz/includes/src/Mage_Adminhtml_Block_Dashboard_Diagrams.php(55): Mage_Core_Block_Abstract->toHtml()
#7 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(1893): Mage_Adminhtml_Block_Dashboard_Diagrams->_prepareLayout()
#8 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(27294): Mage_Core_Block_Abstract->setLayout(Object(Mage_Core_Model_Layout))
#9 /home/onemelak/public_html/magento/etiz/includes/src/Mage_Adminhtml_Block_Dashboard.php(66): Mage_Core_Model_Layout->createBlock(‘adminhtml/dashb…’)
#10 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(1893): Mage_Adminhtml_Block_Dashboard->_prepareLayout()
#11 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(27294): Mage_Core_Block_Abstract->setLayout(Object(Mage_Core_Model_Layout))
#12 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(27310): Mage_Core_Model_Layout->createBlock(‘adminhtml/dashb…’, ‘dashboard’)
#13 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(27077): Mage_Core_Model_Layout->addBlock(‘adminhtml/dashb…’, ‘dashboard’)
#14 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(27043): Mage_Core_Model_Layout->_generateBlock(Object(Mage_Core_Model_Layout_Elem ent), Object(Mage_Core_Model_Layout_Element))
#15 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(27048): Mage_Core_Model_Layout->generateBlocks(Object(Mage_Core_Model_Layout_Elem ent))
#16 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(13507): Mage_Core_Model_Layout->generateBlocks()
#17 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(13432): Mage_Core_Controller_Varien_Action->generateLayoutBlocks()
#18 /home/onemelak/public_html/magento/etiz/includes/src/Mage_Adminhtml_Controller_Action.php(275): Mage_Core_Controller_Varien_Action->loadLayout(NULL, true, true)
#19 /home/onemelak/public_html/magento/etiz/app/code/core/Mage/Adminhtml/controllers/DashboardController.php(40): Mage_Adminhtml_Controller_Action->loadLayout()
#20 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(13582): Mage_Adminhtml_DashboardController->indexAction()
#21 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(17927): Mage_Core_Controller_Varien_Action->dispatch(‘index’)
#22 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(17484): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http) )
#23 /home/onemelak/public_html/magento/etiz/includes/src/__default.php(20061): Mage_Core_Controller_Varien_Front->dispatch()
#24 /home/onemelak/public_html/magento/etiz/app/Mage.php(683): Mage_Core_Model_App->run(Array)
#25 /home/onemelak/public_html/magento/etiz/index.php(87): Mage::run(”, ‘store’)
#26 {main}