Inside CivilCAD, go to Configuración → Rutas :
Even on 64-bit, AutoCAD 2010 runs WOW64 (Windows on Windows 64) for 32-bit ARX files. Force a larger user-mode address space: civilcad 2008 para autocad 2010 64 bits better
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\AECsoft\CivilCAD\2008\Versions Inside CivilCAD, go to Configuración → Rutas :