Linux fedora core 2

How can I stop dhcp client chaning hostname that it gets from dhcp server. In sort I want to have hostname equal to instead of dch<ip address>
I also changed HOSTNAME = in \etc\sysconfig\network and still getting following alert message:

Could not look up internet address for xxxxx. This will prevent GNOME from operating correctly. It may be possible to correct the problem by adding xxxxx to the file /etc/hosts.

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Any input to resolve this issue is appreciated.