Solution:
1. Delete the content from directory 'C:Program Files (x86)Dfm'.
2. Copy the content from directory 'O:DRXProgrammeDFMUpdUpdate' into the under point 1 mentioned directory without the sub folders 'PPPM Favorites', 'ProMIT Favorites' und 'Vorlage'.
3. Finally copy the content from sub folder 'C:Program Files (x86)DfmTelDatenNA' into the folder 'C:Program Files (x86)Dfm' and delete the folder 'C:Program Files (x86)DfmTelDaten'.