Hi and welcome on board.
Could you please provide more details like EPESI version, PHP version, etc? It would be faster if I don't have to ask about it.
Probably you've got some issues with autoloading feature used by roundcube. At first make sure that you've got this file modules/CRM/Roundcube/RC/program/lib/Roundcube/rcube_utils.php and it's readable by server.
PS. wrong forum category
