In C3D 2013 Pressure Pipes as soon as I try to do a SW, SE, etc. Isometric through a Viewport or just in model space I get an error message and thrown out of the file. If I reference the file into another C3D drawn it works without errors and I can save then close that file, however that same file will never open back up and it gives error messages when trying. I tried purge, audit, recover and nothing works. Any help is greatly appreciated. I am using an HP Z600 12GB DDR3 Memory computer with 160gb 10k rpm hard drive.