My Hibernate version:
3.1.3

Name and version of the database
Mysql 5

Hi every body.
I had been using Hibernate 2 in my web application.I used to open and close the session for every transaction and I had no problem with save.
then I migrated to hibernate 3 specially for its default lazy loading mechanism in order to improve performance. now I use long term session that spans more then one transaction. now my problem is unstable bahavior when saving. it sometimes doesn't save with no exception thrown. sometimes objects are saved but after a period of time. I tried session.flush() but it doesn't always sloves the problem I eventhough tried to close the session when I could do it but this too didn't solve it. the problem I think, doesn't relate to the mapping since it is
seen for many kinds of objects of my domain model.

your immediate help is appreciated.