title: Magento - Can't view any products in frontend or backend
body: <p>Yesterday everything was fine in the webshop.
  Since today all products in the frontend display a 404 error. When I try to view the product in the backend I get the following error:  </p>
  
  <p>Source model "qquoteadv/source_conditions" not found for attribute "quotemode_conditions"</p>
  
  <pre><code>Trace:
  #0 /home/users/ftp/site.com/shop/app/code/core/Mage/Eav/Model/Entity/Attribute/Abstract.php(387): Mage::exception('Mage_Eav', 'Source model "q...')
  #1 /home/users/ftp/site.com/shop/app/code/core/Mage/Adminhtml/Block/Widget/Form.php(201): Mage_Eav_Model_Entity_Attribute_Abstract-&gt;getSource()
  #2 /home/users/ftp/site.com/shop/app/code/core/Mage/Adminhtml/Block/Catalog/Product/Edit/Tab/Attributes.php(70): Mage_Adminhtml_Block_Widget_Form-&gt;_setFieldset(Array, Object(Varien_Data_Form_Element_Fieldset), Array)
  #3 /home/users/ftp/site.com/shop/app/code/core/Mage/Adminhtml/Block/Widget/Form.php(144): Mage_Adminhtml_Block_Catalog_Product_Edit_Tab_Attributes-&gt;_prepareForm()
  #4 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Block/Abstract.php(862): Mage_Adminhtml_Block_Widget_Form-&gt;_beforeToHtml()
  #5 /home/users/ftp/site.com/shop/app/code/core/Mage/Adminhtml/Block/Catalog/Product/Edit/Tabs.php(79): Mage_Core_Block_Abstract-&gt;toHtml()
  #6 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Block/Abstract.php(238): Mage_Adminhtml_Block_Catalog_Product_Edit_Tabs-&gt;_prepareLayout()
  #7 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Model/Layout.php(456): Mage_Core_Block_Abstract-&gt;setLayout(Object(Mage_Core_Model_Layout))
  #8 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Model/Layout.php(472): Mage_Core_Model_Layout-&gt;createBlock('adminhtml/catal...', 'product_tabs')
  #9 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Model/Layout.php(239): Mage_Core_Model_Layout-&gt;addBlock('adminhtml/catal...', 'product_tabs')
  #10 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Model/Layout.php(205): Mage_Core_Model_Layout-&gt;_generateBlock(Object(Mage_Core_Model_Layout_Element), Object(Mage_Core_Model_Layout_Element))
  #11 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Model/Layout.php(210): Mage_Core_Model_Layout-&gt;generateBlocks(Object(Mage_Core_Model_Layout_Element))
  #12 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Controller/Varien/Action.php(344): Mage_Core_Model_Layout-&gt;generateBlocks()
  #13 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Controller/Varien/Action.php(269): Mage_Core_Controller_Varien_Action-&gt;generateLayoutBlocks()
  #14 /home/users/ftp/site.com/shop/app/code/core/Mage/Adminhtml/Controller/Action.php(275): Mage_Core_Controller_Varien_Action-&gt;loadLayout(Array, true, true)
  #15 /home/users/ftp/site.com/shop/app/code/core/Mage/Adminhtml/controllers/Catalog/ProductController.php(250): Mage_Adminhtml_Controller_Action-&gt;loadLayout(Array)
  #16 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Controller/Varien/Action.php(419): Mage_Adminhtml_Catalog_ProductController-&gt;editAction()
  #17 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action-&gt;dispatch('edit')
  #18 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Controller/Varien/Front.php(176): Mage_Core_Controller_Varien_Router_Standard-&gt;match(Object(Mage_Core_Controller_Request_Http))
  #19 /home/users/ftp/site.com/shop/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front-&gt;dispatch()
  #20 /home/users/ftp/site.com/shop/app/Mage.php(683): Mage_Core_Model_App-&gt;run(Array)
  #21 /home/users/ftp/site.com/shop/index.php(86): Mage::run('', 'store')
  #22 {main}
  </code></pre>
  
  <p>Has anyone had a similiar error or know how to fix it?
  Help would be appreciated as the website is live and needs to be fixed ASAP.</p>