I have an app (optimistic table buffering) that generates more records in a shorter time than this, and I don't have ANY problems with the header being locked. From my experience, this message appears when somebody does have the table locked through a REPLACE all or REPLACE FOR or DELETE ALL or DELETE FOR, but never has INSERT INTO caused this for me. I don't use any specific locking procedure except in the routine that generates primary keys.
Erik Moore
Clientelligence