Glad you've fixed it.
Please update your forum profile with the output of the following:
I've had the same problem with a fresh CentOS 5.4 install. The problem is not the formatting of the /etc/hosts file but is caused by the fact that perl is not installed.
During the installation install.sh calls /util/utilfunc.sh and on line 370 of this script perl is used to perform a function.
yum install -y perl
will solve the problem.