Hibernate version:3.0

Name and version of the database you are using:Oracle 10g

I am using annotations to map a string field to clob using @Lob(type=LobType.CLOB), in my code I am doing the following steps.
reading the object, setting fields (but not touching the clob)

then i am calling saveOrUpdate on the object and it sets again the clob field and appends a sequence of the following characters:?@ which are retrieved on the next read of the object.

it happens on selected records which clobs are not even longer than the ones that works OK.

I am seeing a select for the record and then update, i am using one trascation (with a couple of nested ones) to wrap the select and update.

sorry for the lack of more information but I am almost 100% sure the problem is on the store of a clob, I just couldnt find the difference between the correct and corrupted clobs