In /var/log/mesages lots of :-
May 20 09:50:01 Server1 : error getting update info: Cannot retrieve repository metadata (repomd.xml) for repository: epel. Please verify its path and try again
If I run yum -d 9 check-update it hangs at Setting up Package Sacks
Found out that another admin had added epel.repo in /etc/yum.repos.d
As we use a proxy to connect to Redhat it appears there is a feature that if you add repos then you need to update /etc/yum.conf yum will not pick up the proxy settings from /etc/sysconfig/rhn/up2date
Adding proxy=http://proxy.mydomain.co.uk:8080 to /etc/yum.conf soleved the problem.