we have been experiencing this problem in our production environment since we have migrated from Oracle9i to Oracle 10G. However we could not generate this problem in local environment. Please see our database settings (same to production environment).
Our JSP fields allow 1000 characters to be inserted in Varchar2(4000) fields. So even if a full length String of 1000 characters of 4-byte each is entered by a user it should be inserted into the database without any problem.
Could you please tell us what might be the reason of getting this exception?