hey guys, I also ran into the same error when re-installing Centos 6.4 x86_64.
here's what my system had:
# egrep -i module.so /etc/php.d/*
It seems module.so is a default/dummy setting for new modules, as I couldn't find module.so anywhere. Though I did find mcrypt.so, so I edited mcrypt.ini as below, which fixed my error.
# cat /etc/php.d/mcrypt.ini
; Enable mcrypt extension module
Hope that helps.