How can I downgrade my version of PHP ?
Iphp 5.3 on Fedora 17 or Redhat using atomic repo.
You will need to remove php and httpd first (not compulsory)
yum remove php
yum remove httpd
Add the following at the end of /etc/yum.conf(if required)
Install php from atomic repo
wget -q -O - http://www.atomicorp.com/installers/atomic | sh
yum install php
More details at