Admin Fatal Error. No Login Screen

Problem: Admin Fatal Error. No Login Screen 

Fatal error: Call to a member function getUsername() on a non-object in /home/site/public_html/app/design/adminhtml/default/default/template/page/header.phtml on line 33 

Solution: 

check the config file adminhtml/default/default/layout/main.xml add this code to your main.xml :

<adminhtml_dashboard_customersmost>
        <block type="core/text_list" name="root" output="toHtml">
            <block type="adminhtml/dashboard_tab_customers_most" name="adminhtml.dashboard.tab.customers.most"/>
        </block>
    </adminhtml_dashboard_customersmost>

    <adminhtml_dashboard_customersnewest>
        <block type="core/text_list" name="root" output="toHtml">
            <block type="adminhtml/dashboard_tab_customers_newest" name="adminhtml.dashboard.tab.customers.newest"/>
        </block>
    </adminhtml_dashboard_customersnewest>

    <adminhtml_dashboard_productsviewed>
        <block type="core/text_list" name="root" output="toHtml">
            <block type="adminhtml/dashboard_tab_products_viewed" name="adminhtml.dashboard.tab.products.viewed"/>
        </block>
    </adminhtml_dashboard_productsviewed>

    <adminhtml_index_login>
        <block type="core/text_list" name="root" output="toHtml">
            <block type="adminhtml/template" name="content" template="login.phtml">
                <block type="core/text_list" name="form.additional.info" />
            </block>
        </block>
    </adminhtml_index_login>

    <adminhtml_index_forgotpassword>
        <block type="core/text_list" name="root" output="toHtml">
            <block type="adminhtml/template" name="content" template="forgotpassword.phtml">
                <block type="core/text_list" name="form.additional.info" />
            </block>
        </block>
    </adminhtml_index_forgotpassword>