Importing AutoCad files

OK, i have CD 12.. I design aircraft dial faces and panels with it. Basically, it's just boxes, circles and text. One of my customers always sends me an autocad file (.dwg and .dxf) and I am always able to open them, but today it aint working.. I'm getting either error opening or when I am able to try to open it it doesnt display. The closest i get is when I get the dialog box about the .dxf file I click on front view, auto reduce nodes or words to that effect, and then hit OK, It looks like it's working but nothing displays

 I'm assuming that the customer might have a newer version of autocad that CD 12 wont open. What newer version of CD must I purchase to get this file open?