Thanks to Pauli and Jon I got this working again.
I too am running CentOS 5 with the latest Plesk and Sitebuilder.
yum remove sitebuilder php5sb
cd /tmp
rm -rf *
rm -rf /root/parallels
rm -rf /usr/local/sitebuilder
rpm -e --justdb php5-ioncube-php52
Re-installed Plesk Sitebuilder using autoinstaller and had no issues.