Error when deleting a selected row from jtable (swing & hibernate)

[tugfan]

I have an error when I delete a selected row from JTable (table "user" ) (I'm using Hibernate):\[code\]a different object with the same identifier value was already associated with the session\[/code\]also the selected row is not deleted but the row after become deleted and also its deleting me all the records from a table "role" (which have association with this table "user" (n-n))I really don't know where is the problem here. Please I need your help