CodeIgniter lost my session

[eluser]WanWizard[/eluser]
You shouldn't use the session as a replacement for your database.
Only store the information in the session that is required to maintain state in your application.

From an authentication / authorisation perspective, the user_id and user_name, and the user's rights structure, is sufficient for the application. The single form that needs to display more information about the user can retrieve it from the database using the stored user_id.