How to repair "error loading feed data" in Joomla 1.5

After completing Joomla 1.5 installation process, we usually going to the Joomla administrator page. But when I go to an administrator page joomla 1.5, page load very slow, and after it finish loading page, there is an error message "Error loading feed data". In this installation process, i also installing Joomla 1.5 sample data. After googling for a while, i found how to repair these errors.