TQuery - Capability Not Supported Problem

I have two apps, one written with C++ Builder V1 and the other with
Delphi 3. The C++ app writes to a database table and the Delphi app
reads records then deletes them from this table. To keep the Delphi app
current with the database table I use:
     qryEvent.Close;
     qryEvent.Open;
The C++ app uses all Dbi calls to interface with the database.
When traffic is relatively high (1 transaction/second being written) I
sometimes get one of two errors on the "qryEvent.Open" (Delphi app)
call: either
    "Capability Not Supported"   or  "Invalid Field Value"
The SQL placed in the TQuery component is never changed and reads:
   "SELECT * FROM 'Event.DB' ORDER BY Seqno"
My executables are in one directory and the database is in a different
directory and I noticed that there are two sets of ParadoxUsers.LCK
files; one set in each directory.
Do I have a table locking problem?  I added a DbiAcqTableLock() in the
C++ code which appears to clear up the problem. I fear it is a timing
problem due to its intermittancy.