Need help with ODBC error - Mailing list pgsql-interfaces

I'm working with VB5 connecting to PostgreSQL V6.5 via PsqlODBC.

When I try to update a record set (in optimistic batch mode), I get
the following error: (obtained from DBEngine object)

S1000: Error while executing the query;
ERROR:  fmgr_info: function 707904: cache lookup failed

any idea what's happening? I've never had this problem before.