Fatal Error when closing AutoCAD CIVIL 3D 2012

I posted this issue in some forums but I was still unable to repair it.
Every time I close my AutoCAD CIVIL 3D 2012, this error comes up.
Even though I can still access AutoCAD when I just clicked on the OK button, it is so frustrating that every after closing the program, this error comes next.
I am worried that it may cause problems in the future.
How can I fix this?

AutoCAD
FATAL ERROR: Unhandled Access Violation Reading 0xcb899c88 Exception at e89f9242h
OK
