Problem with .docx files

It seems irrespective of size PDFCerator caanot handle MS-WORD .docx files. On my Windows 7 machine it gives an error msage:

Error No.: 53 (File not found: gsdll32.dll)

Modul: ModGsApi

Procedure: CallGS

Line: 502000

After saving to a .doc file PDFCreator works fine. Why the problem with new style .docx files?