From the command line.
db yum_repositories setprop updates Exclude kernel,kernel-smp,mkinitrd,mdadm,initscripts
db yum_repositories setprop base Exclude kernel,kernel-smp,mkinitrd,mdadm,initscripts
db yum_repositories setprop centosplus Exclude kernel,kernel-smp,mkinitrd,mdadm,initscripts,perl*,httpd,mod_ssl
expand-template /etc/yum.conf
yum clean all
yum update \
--disablerepo=* \
--enablerepo=base \
--enablerepo=updates \
--enablerepo=smeos \
--enablerepo=smeupdates \
--enablerepo=smeaddons
If it still fails look in /etc/e-smith/db and clean out the yum directories (except the repositories one although you could if you don't have any custom repositories).
rm /home/e-smith/db/yum_available
rm /home/e-smith/db/yum_installed
rm /home/e-smith/db/yum_updates
signal-event post-upgrade
signal-event reboot