I have the same problem as posted and answered elsewhere. The solutions there didn't resolve my problem.
One day, I could no longer import .dxf files, even though I've done this several times a day, forever. The files I'm trying are from the same source as ever, and even files that I could import the day before could not be imported. The file type is no longer listed in the open file dialog box for the import.
I have tried many things: reset CorelDRAW, reinstalled the program (X6 Student), and tried all of the update/patches (none of which would install--do I need a membership to apply them, as suggested in the info?)
Any further ideas would be appreciated.