>I make DSNless connections to either a VFP DBC or an SQL Server database based on values in an INI file. I can do a SELECT or an UPDATEe on both databases using the same statement fine. Whenever I try an INSERT, the statement works fine against SQL Server, but fails against the VFP DBC. Any hints on how to start tracking down this one?

You can use AERROR() function to get details about ODBC error.