I just installed Civil 3D 2012 64 bit on a new computer running Windows 8. It starts up fine, but when I pull up a drawing, about 1 or 2 minutes later, the program shuts down and I have to restart Civil 3D. I've pulled up several different drawings from different sources, and it does the same thing. First, a window pops up for a split second, and I can't read the contents of the window. Then, I get the window that says Civil 3D is shutting down. How do I fix this?