We have installed this extension ([login to view URL]) on a new 1.4 website still in development. The frontend has now crashed. The error report starts with:
a:5:{i:0;s:86:"Invalid backend model specified: accesscontrol/entity_attribute_backend_customergroups";i:1;s:5016:"#0 /var/www/vhosts/[login to view URL](338): Mage::exception('Mage_Eav', 'Invalid backend...')
I need a developer to either get this extension working correctly, or if that is not possible, remove it and get the frontend working (uninstalling does not work).