Wed Aug 28 10:44:02 2012 Errors in file /opt/app/oracle/admin/DB_NAME/udump/INSTANCE_NAME2_ora_22435.trc: ORA-00600: internal error code, arguments: [kzdlk_zt2 err], , , , , , , 
On Oracle metalink there's a very valuable tool to debug and analyze some ora-600 error: it's called "ORA-600/ORA-7445 Error Look-up Tool" and you can find it looking for the ID 153788.1
From this web page I selected "ORA-600" as Error Code, "kzdlk_zt2 err" as Error Code First Argument and finally 10.2.0.4 as Oracle RDBMS Version.
It soon prompted me asking to be redirected on ORA-600 [kzdlk_zt2 err] [ID 1309705.1] document.
The note states that the error indicates the wrong syntax has been used to create a database link.
When the database link was created, the password was established using the syntax IDENTIFIED BY VALUES as compared to the document syntax of IDENTIFIED BY.
It states also that the use of IDENTIFIED BY VALUES is reserved for internal Oracle use only. While earlier Oracle releases allowed the use of IDENTIFIED BY VALUES, this is not documented as being valid syntax.
From Oracle release 10gR2, database links must be created using the documented syntax.
And the solution is: recreate the database link using valid syntax,
CREATE DATABASE LINK dblink CONNECT TO user IDENTIFIED BY password USING 'connect_string';That's all.