Access Violation with TQuery and Delphi 3.02 under NT 4.0

I'm trying to use TQuery with ODBC Driver Sql Anywhere.
I have two databases component and 2 queries with a master/detail schema: I
read information in the first query from the first database then I put them
in the second database.
When I put an another query on the form which do nothing I have access
violation on the ExecSQL Command on the first Query.
Please Help