Problem installing odoo in account

I have been trying to install odoo into an account, it all appeared to be going well but on completion of the install process, I get a
Internal Server Error
The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.

This happens whether I use the ip address or the domain name, all processes appear to be running fine when checked but no front end access.

Checking back on the install I found a collection of errors relating to
Error: Package: psysh-0.8.3-1.el7.noarch (epel)
Requires: php-date
also errors relating to package drush.

I have used the instructions from odoo.com and a set of instructions specific to centos from a third party site. Same result for both.

I am wondering if I would have better luck compiling from source?
Is the fact that postgres is already install causing an issue.