Hello guys, thanks for your answers:
Yep, i'm using the thinymce editor, but the problem aparently isn't on the editor itself; the option (sadli) in the db sounds more aprouching, and if the change needs a reset of the db... Well isn't a option.
When you are editing or creating the message, you don't have any problem writing it; you can put in the editor any characters that you want, and when you post it, the post appears completely. But if you wait ... a few minutes and refresh the page, the post is chuncked at ... well aproximateli at the 70000 character. So the problem komes from the db, that don't save all the text and only the size that it is capable.
thanks for your answer!bb