Error 5 is Duplicate Key.  Not sure if you have a duplicate entry of a file in your data dictionary or what.  
 
If you have a CD of the same DBA version you are running, and you do not have extra companies created, there is a set of standard DDF files in the SUPPORT folder on the CD.  But they only have the default and 99 company in them, won't work if you have other companies.  
 
Try Maintain Database and see if it works - that is really the only DBA function that uses the DDF files.   If you are trying to do some other kind of ODBC connection, you may want to go to UT-A and run ODBCDDF in the company that you are trying to connect to.  That creates a set of company specific DDF files in the folder of the company.

Try UT-A, program MDBFXREG.  Then exit DBA and come back in, see if that helps.