EM- java.lang.Exception:UnknownHostException

Environment : Windows XP sp3, Oracle 10.2.0.4.0

Problem : When i connect to EM console, with SYS user. it thrown an exception error message

Error : java.lang.Exception: UnknownHostException sending request :: naachi-514ccc13

Cause : Recently I was changed the server hostname. previously it was "naachi-514ccc13", now it is "naachi".

Solution : d:\> emca -config dbcontrol db -repose recreate

The following action will be performed automatically by the above single line.

>>> Stop the database control
>>> Drop the database control
>>> Create the database control
>>> Start the database control

Status : successfully problem solved.