Are you using pessimistic table locking anywhere in your app or changing a connection userid programmatically (such as for creating views on the fly)? Other than that, some things to check are: if a view or a table in a database is open shared, the database is also shared. However, commands that directly relate to the database (.DBC file) structure and commands that involve the creation or deletion of objects require exclusive use of the database such as CREATE TABLE, MODIFY STRUCTURE, ALTER TABLE, ADD TABLE, RENAME TABLE, CREATE SQL VIEW, MODIFY VIEW, DELETE VIEW, RENAME VIEW, CREATE CONNECTION, MODIFY CONNECTION, DELETE CONNECTION, RENAME CONNECTION, INDEX ON (except on a view), DELETE TAG, CREATE TRIGGER, DELETE TRIGGER, APPEND PROCEDURES, COPY PROCEDURES, MODIFY PROCEDURE, COMPILE DATABASE, PACK DATABASE, and VALIDATE DATABASE.

Also, are you using .dbfs or what is the backend? Are you having connection timeouts or connectivity drops at the same locations? (Remember client32 will re-establish a connection that is dropped automatically and the connection number will NOT necessarily be the same). What code is being processed when this happens?