I get a fatal error message: Unhandled Access Violation Reading 0x7ffffffd Exception at 6d9cc265h when i try to do anything in a drawing. Has anyone seen this error type before?
Yes, seen this many times before over the years. I have tried many things to fix, such as saving back to earlier versions, saving as DXF. Sometimes it fixes, sometimes it doesn't.
Do you have access to an earlier version of Civil 3D? If so can you open and modify with this (you will get a notice regarding proxy graphics and earlier version) and see if you can copy all objects to a new drawing.
Does the drawing have XREFs? If so unload them using the reference manager (I think you can) or with an earlier version of civil 3D
As said earlier can you save as a DXF file? and copy all objects to a new file?
Can you WBLOCK the objects out of the drawing?
Have you installed any other software recently that may be interfering with your Civil 3D or the amount of memory you have access to?