redo the registration:
1. delete /etc/sysconfig/rhn/systemid
2. logon to https://rhn.redhat.com/
(hey they have a new look
). and delete your system profile.
3. then re-register (up2date --register)
I forgot - u can just move your entitlements from the old system entry to your new system. (i got lost in the new RHN web