修改主机名导致oracle实例无法启动暨如何修改hostname

操作系统是32位的Linux 5.1:
# cat /etc/redhat-release
# Red Hat Enterprise Linux Server release 5.1 (Tikanga)

数据库版本是10.2.0.3.0:

SQL> select * from v$version;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Prod
PL/SQL Release 10.2.0.3.0 - Production
CORE    10.2.0.3.0      Production
TNS for Linux: Version 10.2.0.3.0 - Production
NLSRTL Version 10.2.0.3.0 - Production

network文件内容如下：
$ cat /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=localhost.localdomain

hosts文件内容如下：
$ cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1               localhost.localdomain localhost
::1             localhost6.localdomain6 localhost6

在没有修改主机名的情况下一切正常，因为想要规范linux服务器的名字，欲修改Linux的hostname，但是修改后数据库无法启动，有此经验的朋友请指点，感谢ing
修改主机名我尝试了两种：
第一种.直接修改名字，不重启机器
# hostname oratest
第二种.修改network文件，重新启动机器
$ cat /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=oratest

修改主机名之后问题现象如下：
[oracle@oratest ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.3.0 - Production on Mon Jan 12 05:05:45 2009

Copyright (c) 1982, 2006, Oracle.  All Rights Reserved.

Connected to an idle instance.

SQL> startup;
ORA-00600: internal error code, arguments: [keltnfy-ldmInit], [46], [1], [], [], [], [], []


[oracle@oratest ~]$ emctl start dbconsole
TZ set to PRC
Exception in getting local host
java.net.UnknownHostException: oratest: oratest
        at java.net.InetAddress.getLocalHost(InetAddress.java:1191)
        at oracle.sysman.emSDK.conf.TargetInstaller.getLocalHost(TargetInstaller.java:5488)
        at oracle.sysman.emSDK.conf.TargetInstaller.main(TargetInstaller.java:4102)
Exception in getting local host
java.net.UnknownHostException: oratest: oratest
        at java.net.InetAddress.getLocalHost(InetAddress.java:1191)
        at oracle.sysman.emSDK.conf.TargetInstaller.getLocalHost(TargetInstaller.java:5488)
        at oracle.sysman.emSDK.conf.TargetInstaller.main(TargetInstaller.java:4102)
OC4J Configuration issue. /oracle/u01/app/oracle/product/10.2.0/db_1/oc4j/j2ee/OC4J_DBConsole_null_ora10g not found.