While attempting to perform an Export DXF/DWG operation, the task could fail with the error "Invalid file name", especially if you run NX in both managed and native modes on the same computer.
It could be possible that the file path/name has been recorded from managed NX into your dialog memory and thus cause the native session translator to fail when the dialog is being built with the managed path which it cannot not resolve in a native NX session.
Solution To resolve the issue perform the following:
Menu--> Preferences--> User Interface--> Options--> Dialog Boxes--> Reset Dialog Memory
This should resolve the problem and allow you to access the DXF/DWG translator.
Notes and References
Hardware/Software Configuration Platform: INTL64
OS Version: 1064