Delphi1 - Paradox-Tables + no fileaccess within a DLL

I've a big problem:
I've an Application written in Delphi 1. This application uses a DLL
written in Borland C++ 3.1. In the DLL are done some file-operations.
Everything worked fine till I added some tables connected with a Paradox
5.0 database to the Delphi-application. When the tables are open, the
DLL is not able to create a file, not even able to write to an existing
file. I tried everything.  SetHandleCount didn't work.

Please help